Human chemotactic cytokine

ABSTRACT

The invention relates to isolated and/or recombinant nucleic acids which encode a human chemotactic cytokine designated human eotaxin, and to isolated and/or recombinant human eotaxin proteins or polypeptides, including synthetic polypeptides. The invention further relates to recombinant nucleic acid constructs, comprising a nucleic acid which encodes a human eotaxin, a portion thereof, or a variant; to host cells comprising such constructs, useful for the production of recombinant human eotaxin; and to antibodies reactive with human eotaxin, useful in in vitro methods, diagnosis and/or therapy. Also provided are methods of use of the eotaxin proteins, e.g., in the recruitment of eosinophils to a particular site or in the treatment of allergic conditions. Human eotaxins can be used to identify inhibitors (e.g., antagonists) or promoters (agonists) of human eotaxin, which can be used to selectively modulate leukocyte function, in inflammatory and autoimmune diseases, or in infections.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/900,700, filed on Sep. 13, 2007, which is a divisional of U.S.application Ser. No. 11/133,140, filed on May 19, 2005, now U.S. Pat.No. 7,285,620, which is a continuation of U.S. application Ser. No.08/494,093, filed on Jun. 23, 1995, now U.S. Pat. No. 7,265,201. Theentire teachings of the above applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

Chemokines, also referred to as intecrines, are soluble, low molecularweight members of the cytokine family which have chemoattractantfunction. Chemokines are capable of selectively inducing chemotaxis ofthe formed elements of the blood (other than red blood cells), includingleukocytes such as eosinophils, basophils, neutrophils(polymorphonuclear leukocytes), lymphocytes (e.g., T and B cells), andother blood and tissue cells such as mast cells and macrophages. Achemoattractant protein is capable of attracting leukocytes (such aseosinophils or other leukocyte subsets), and of inducing accumulationand/or activation of leukocytes (such as eosinophils or other leukocytesubsets) in vitro and/or in vivo. In addition to stimulating chemotaxis,other changes can be selectively induced by chemokines in responsivecells, including changes in cell shape, transient rises in theconcentration of intracellular free calcium ([Ca²⁺]_(i)), granuleexocytosis, integrin upregulation, formation of bioactive lipids (e.g.,leukotrienes) and respiratory burst, associated with leukocyteactivation. Thus, the chemokines are early triggers of the inflammatoryresponse, causing inflammatory mediator release, chemotaxis andextravasation to sites of infection or inflammation.

The chemokines characterized to date are related in primary structure.They share four conserved cysteines, which form disulphide bonds. cDNAcloning and biochemical characterization of several chemokines hasrevealed that the proteins typically have a leader sequence of about20-25 amino acids, which is cleaved upon secretion to yield a matureprotein of approximately 92-99 amino acids. Based on the conservedcysteine motif, the family is divided into two branches, designated asthe C—C chemokines and the C—X—C chemokines, in which the first twoconserved cysteines are adjacent or are separated by an interveningresidue, respectively. Baggiolini, M. and C. A. Dahinden, ImmunologyToday, 15: 127-133 (1994)).

The C—X—C chemokines include a number of chemoattractants which arepotent chemoattractants and activators of neutrophils, such asinterleukin 8 (IL-8), and neutrophil-activating peptide 2 (NAP-2). TheC—C chemokines include molecules such as human monocyte chemotacticproteins 1-3 (MCP-1, MCP-2 and MCP-3), RANTES (Regulated on Activation,Normal T-cell Expressed and Secreted), and the macrophage inflammatoryproteins 1α and 1β (MIP-1α and MIP-1β), which have been characterized aschemoattractants and activators of monocytes or lymphocytes, but do notappear to be chemoattractants for neutrophils. For example, recombinantRANTES is a chemoattractant for monocytes, as well as for memory T cellsin vitro (Schall, T. J. et al., Nature, 347: 669-671 (1990)).

The C—C chemokines are of great interest because of their potential rolein allergic inflammation. For example, MCP-1 induces exocytosis of humanbasophils, resulting in release of high levels of inflammatorymediators, such as histamine and leukotriene C₄. Similarly, there isgreat interest in the receptors for the C—C chemokines, which triggerthese cellular events in response to chemokine binding. A receptor forC—C chemokines has recently been cloned and is reported to bind MIP-1αand RANTES. Accordingly, this MIP-1α/RANTES receptor was designated C—Cchemokine receptor 1 (Neote, K. et al., Cell, 72: 415-425 (1993); Horuk,R. et al., WO 94/11504, published May 26, 1994; Gao, J.-I. et al., J.Exp. Med., 177: 1421-1427 (1993)). An MCP-1 receptor has also beencloned (Charo, I. F. et al., Proc. Natl. Acad. Sci. USA, 91: 2752(1994)).

The MCP-1 receptor and the C—C chemokine receptor 1 are predicted tobelong to a family of seven transmembrane spanning G-protein coupledreceptors. This family of G-protein coupled (serpentine) receptorscomprises a large group of integral membrane proteins, containing seventransmembrane-spanning regions. The ligands of these receptors include adiverse group of molecules, including small biogenic amine molecules,such as epinephrine and norepinephrine, peptides, such as substance Pand neurokinins, and larger proteins, such as chemokines. The receptorsare coupled to G proteins, which are heterotrimeric regulatory proteinscapable of binding GTP and mediating signal transduction from coupledreceptors, for example, by the production of intracellular mediators.

The cloning and sequencing of two IL-8 receptor cDNAs reveals that theseC—X—C receptor proteins also share sequence similarity with seventransmembrane-spanning G protein-coupled receptor proteins (Murphy P. M.and H. L. Tiffany, Science, 253: 1280-1283 (1991); Murphy et al., WO93/06299; Holmes, W. E. et al., Science, 253: 1278-1280 (1991)).Additional receptors for chemotactic proteins such as anaphylatoxin C5aand bacterial formylated tripeptide fMLP have been characterized bycloning and been found to encode receptor proteins which also sharesequence similarity to these seven transmembrane-spanning proteins(Gerard, N. P. and C. Gerard, Nature, 349: 614-617 (1991); Boulay, F. etal., Biochemistry, 29: 11123-11133 (1990)). Although a number of otherproteins with significant sequence similarity and similar tissue andleukocyte subpopulation distribution to known chemokine receptors havebeen identified and cloned, the ligands for these receptors remainundefined. Thus, these proteins are referred to as orphan receptors.

The isolation and characterization of additional genes and the encodedchemokine, and the characterization of the corresponding receptor(s), isessential to an understanding of the interaction of chemokines withtheir target cells and the events stimulated by this interaction,including chemotaxis and cellular activation of leukocytes.

SUMMARY OF THE INVENTION

The present invention relates to isolated and/or recombinant nucleicacids which encode human chemotactic cytokines designated humaneotaxins. The invention further relates to recombinant nucleic acidconstructs, such as plasmids or retroviral vectors, which contain anucleic acid which encodes a protein of the present invention or portionthereof. The nucleic acids and constructs can be used to producerecombinant human eotaxin. In another embodiment, the nucleic acidencodes an antisense nucleic acid which can hybridize with a secondnucleic acid encoding a human eotaxin of the present invention, andwhich, when introduced into cells, can inhibit the expression of thepolypeptide.

Another aspect of the present invention relates to proteins orpolypeptides, referred to herein as isolated and/or recombinant humaneotaxin. The recombinant human eotaxin proteins and eotaxin variants ofthe present invention can be produced in host cells as described herein.In one embodiment, a human eotaxin is characterized by high affinitybinding to leukocytes, particularly eosinophils and/or the ability toinduce leukocyte accumulation and/or chemotaxis.

Antibodies reactive with the proteins of the present invention can beproduced using a human eotaxin, a variant, or portion thereof asimmunogen, for example. Such antibodies or fragments thereof are usefulin therapeutic, diagnostic and research applications. For example, theantibodies can be used in the purification and study of human eotaxin,the identification of cells which express eotaxin, and the detection ofthe presence of abnormal levels of eotaxin in a sample.

Also encompassed by the present invention are methods of identifyinginhibitors (e.g., antagonists) or promoters (agonists) of human eotaxinfunction. For example, human eotaxin or variants thereof can be used inassays designed to identify antagonists which block the binding of thechemoattractant protein to its natural receptor(s). In one embodiment,suitable host cells which have been engineered to express a receptor forhuman eotaxin are used in an assay to identify and/or assess theefficacy of inhibitors or promoters of human eotaxin function.

Agents that inhibit (e.g., prevent, reduce (decrease or abolish))production, release or activity of a human eotaxin can be usedtherapeutically in the treatment of inflammatory (e.g., asthma) andautoimmune diseases. In addition, human eotaxin, human eotaxin variants,or agents which act as promoters of human eotaxin function can beadministered to an individual providing a method of selectivestimulation of leukocyte function, which can be useful, for example, inthe treatment of cancer or parasitic infections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1B is an illustration of the nucleotide sequence determined froma genomic clone (Clone 25) encoding human eotaxin (SEQ ID NO:1), and thepredicted amino acid sequence of the protein encoded by the open-readingframe (SEQ ID NO:2). The gene contains two introns. (Standard singleletter amino acid codes are used.)

FIG. 2 is an illustration of the nucleotide sequence determined for acDNA clone encoding human eotaxin (SEQ ID NO:3), and the predicted aminoacid sequence of the protein encoded by the open-reading frame (SEQ IDNO:4).

FIG. 3 is an illustration of one type of transendothelial chemotaxisassay. A culture insert is placed into a container, such as a well in a24-well plate, creating a first (upper) and second (lower) chamberwithin the well. ECV304 endothelial cells are grown in a monolayer onthe polycarbonate membrane on the inner side of the insert. Cells (e.g.,leukocytes, such as eosinophils) to be assessed for a response to asubstance (e.g., a chemokine) are introduced into the top chamber andthe substance is introduced into the bottom chamber. The insert can beremoved, and cells which have migrated from the top chamber through theendothelial layer into the bottom chamber can be detected or counted bya suitable method to assess chemotaxis. For example, cells in the bottomchamber can be collected and counted by microscopy or flow cytometry(e.g., FACS analysis). FIG. 3 also shows the results of an assay inwhich migration of PBMC in response to MCP-1 was determined using afluorescence activated cell sorter. Cell size and side scatter of humanPBMC (left); background migration in a “no chemokine” control (center);and migration of cells (particularly the monocyte population) inresponse to 100 ng/ml of MCP-1 (right) are plotted.

FIGS. 4A-4D are histograms illustrating the chemotaxis of humanleukocyte subpopulations (FIG. 4A, neutrophils; FIG. 4B, monocytes; FIG.4C, activated T cells; FIG. 4D, eosinophils) in response to 100 ng/ml ofchemokine present in the bottom chamber of a chemotaxis assay (MCP-1,MCP-2, MCP-3, MIP-1α (MIP-1α), RANTES, interleukin-8 (IL-8), IP-10,MIP-1β, or human eotaxin). Chemotaxis plates were incubated at 37° C.for 90 minutes, and the cells which migrated to the bottom chamber werecounted by microscopy (HPF=high power field). This was a representativeexperiment of at least four experiments performed.

FIGS. 5A-5C are bar graphs illustrating the dose response of humaneosinophils to human eotaxin. The chemotaxis of eosinophils in responseto 1, 10, 100, or 1000 ng/ml of eotaxin (present in the bottom chamber)was assessed by FACS counting. The response to 100 ng of RANTES or ofMCP-3 was also assessed. The results obtained with eosinophils fromthree different donors are shown (Donor # 1, FIG. 5A; Donor #2, FIG. 5B;Donor #3, FIG. 5C).

FIGS. 6A-6E are plots of fluorescence intensity over time, illustratingthe calcium flux of human eosinophils in response to various agentsadministered in sequence (arrows indicate time of administration).Eosinophil response to a synthetic human eotaxin (eotaxin), followed byRANTES, and then anaphylatoxin C5a is illustrated in FIG. 6A. Eosinophilresponse to RANTES, followed by eotaxin, followed by anaphylatoxin C5ais illustrated in FIG. 6B. Eosinophil response to MIP-1α, followed byeotaxin, followed by anaphylatoxin C5a is illustrated in FIG. 6C.Eosinophil response to RANTES, followed by repeat exposure to RANTES isshown in FIG. 6D. Eosinophil response to human eotaxin followed byrepeat exposure to human eotaxin polypeptide is shown if FIG. 6E. Allchemokines, as well as C5a, were used at a final concentration of 100nM.

FIG. 7 is a graph illustrating the binding of synthetic human eotaxin toeosinophils. ¹²⁵I-labeled eotaxin was incubated with purifiedeosinophils in the presence of increasing concentrations of eotaxin (⋄),RANTES (□), MIP-1α (Δ), and MCP-3 (◯).

FIG. 8 is a Scatchard plot calculated from the data presented in FIG. 7,which indicates a Kd of 4.7 nM and 2.3×10⁴ binding sites per cell.

FIGS. 9A-9B are graphs illustrating the competitive binding of humaneotaxin with RANTES or MCP-3. Purified human eosinophils were incubatedwith radiolabeled RANTES (FIG. 9A) and increasing concentrations of‘cold’ RANTES (□), ‘cold’ eotaxin (⋄), cold MCP-3 (◯) or ‘cold’ MIP-1α(Δ). Purified human eosinophils were also incubated with radiolabeledMCP-3 (FIG. 9B) and increasing concentrations of ‘cold’ MCP-3 (♦) or‘cold’ eotaxin (▪).

FIG. 10 is a graph illustrating that human eotaxin does not inhibitMIP-1α binding. Butyric acid differentiated HL-60 cells were incubatedwith (a) ‘cold’ MIP-1α (Δ), eotaxin (⋄), RANTES (□), MCP-3 (◯) or IL-8(x); and (b) 0.1 nM radiolabeled MIP-1α, and binding took place.

FIG. 11 is a bar graph illustrating the binding of human eotaxin toCKR-3 transfected L1-2 cells. Radiolabeled eotaxin was incubated with5×10⁵ transfected cells or untransfected L1-2 cells. Hatched bar,without competitor; white bar, with 125 nM unlabeled eotaxin.

FIGS. 12A-12E are histograms illustrating the chemotaxis of L1-2transfectants in response to different chemokines (MCP-1, MCP-2, MCP-3,eotaxin, RANTES, MIP-1α, IL-8 and Groα). The L1-2 pre-B lymphoma cellline was transfected with DNA encoding IL-8 RA, IL-8 RB, MIP-1α/RANTESreceptor (CC CKR-1), MCP-1 receptor (CC CKR-2) or CC—CKR-3, and theeffect of various chemokines, including human eotaxin, on the differenttransfectants was assessed. Cell counting was performed using amicroscope.

FIGS. 13A-13B are histograms illustrating the effect of anti-eotaxinmonoclonal antibodies on eotaxin binding to purified human eosinophils.50 μl of tissue culture supernatants from anti-eotaxin hybridomas wereincubated with 5 μl (10 nM) radiolabeled eotaxin at room temperature for10 minutes. Purified human eosinophils were then added, and binding wasdetermined.

FIG. 14 is a bar graph of the number of eosinophils recruited to skininjection sites in rhesus monkeys. Skin biopsies (6 mm) were taken 4hours after injection of control (BSA), RANTES or synthetic humaneotaxin at the 10, 100 or 1000 pmol doses/site. The results areexpressed as the number of cells recruited per mm² as determined bycomputer assisted morphometrics analysis.

FIG. 15A-15D is an illustration of the nucleotide sequence determinedfrom a genomic clone encoding a human C—C chemokine receptor 3 (CKR-3)protein (also referred to as Eos L2 receptor) (SEQ ID NO:5), and thepredicted amino acid sequence of the protein encoded by the open-readingframe (SEQ ID NO:6).

DETAILED DESCRIPTION OF THE INVENTION Proteins and Peptides

The present invention relates to isolated and/or recombinant (including,e.g., essentially pure) proteins or polypeptides which are humanchemotactic cytokines (chemokines) and are designated human eotaxin.Proteins or polypeptides referred to herein as “isolated” are proteinsor polypeptides purified to a state beyond that in which they exist inmammalian cells. “Isolated” proteins or polypeptides include proteins orpolypeptides obtained by methods described herein, similar methods orother suitable methods, including essentially pure proteins orpolypeptides, proteins or polypeptides produced by chemical synthesis,or by combinations of biological and chemical methods, and recombinantproteins or polypeptides which are isolated. Proteins or polypeptidesreferred to herein as “recombinant” are proteins or polypeptidesproduced by the expression of recombinant nucleic acids of the presentinvention.

As used herein human eotaxin refers to naturally occurring or endogenoushuman eotaxin protein (a human eotaxin protein recovered from a sourcewhich naturally produces human eotaxin, including polymorphic or allelicvariants), including mature eotaxin, and proteins having the same aminoacid sequence as naturally occurring or endogenous human eotaxinprotein. Isolated and/or recombinant human eotaxin is a ligand for oneor more natural or physiological receptor(s) for eotaxin and/or canstimulate eosinophil accumulation and/or attract eosinophils (inducechemotaxis). In one embodiment, isolated (e.g., chemically synthesized)and/or recombinant human eotaxin has the same amino acid sequence as anaturally occurring human eotaxin protein. For example, as shown herein,an isolated protein corresponding to amino acids 24-97 of FIG. 2(predicted mature eotaxin) can bind to a receptor present on humaneosinophils specifically and with high affinity and can inducechemotaxis of eosinophils from humans or other primates. In addition,this isolated human protein can also bind to transfected cellsexpressing human C—C chemokine receptor 3 (CKR-3) and induce chemotaxisof the cells.

As shown herein, the proteins encompassed by the term human eotaxin areeosinophil-specific chemoattractants capable of stimulating eosinophilaccumulation and/or attracting eosinophils (inducing chemotaxis).Eosinophil-specific activity can be assessed in vitro, where theproteins are capable of attracting or inducing chemotaxis ofeosinophils, but do not significantly induce chemotaxis of neutrophils,monocytes or T cells. Eosinophil-specific activity can also be assessedin vivo, where the proteins are capable of specifically inducingaccumulation and/or chemotaxis of eosinophils. For example, uponintradermal injection the polypeptides elicit a predominantlyeosinophilic infiltration.

The invention also relates to isolated and/or recombinant portions orfragments of a human eotaxin. In one embodiment, an isolated and/orrecombinant portion (e.g., a peptide) of human eotaxin has at least onefunction characteristic of a human eotaxin, such as a binding function(e.g., binding to an eotaxin receptor or other receptor); a leukocyteactivation function (e.g., activation of a G protein, induction of rapidand transient increase in the concentration of cytosolic free calcium[Ca²⁺]_(i), induction of exocytosis or inflammatory mediator release,leukocyte integrin activation); and/or a leukocyte stimulation function(e.g., induces accumulation and/or chemotaxis of leukocytes, especiallyof eosinophils such as human or primate eosinophils (haseosinophil-specific chemoattractant activity)). For example, one type ofisolated and/or recombinant human eotaxin fragment can bind a receptorfor eotaxin, but cannot induce leukocyte activation and/or stimulation.In one embodiment, an isolated and/or recombinant human eotaxin portionis an eosinophil-specific chemoattractant capable of stimulatingeosinophil accumulation and/or chemotaxis. Examples of functionalfragments or portions of a human eotaxin include those with deletions ofone or more amino acids from the mature protein which retain one or moreof the above functions. The amino acids which can be deleted can beidentified by screening. For example the N- or C-terminus of the proteincan be deleted in a step-wise fashion and the resulting protein orpolypeptide screened in one or more assays as described herein. Alsoenvisioned are fragments wherein an (i.e., one or more) internal aminoacid is deleted, including deletions of non-contiguous amino acids.Where the resulting protein displays activity in the assay, theresulting protein (“fragment”) is functional.

In an alternative embodiment, an isolated and/or recombinant portion(e.g., a peptide) of human eotaxin has at least one immunologicalproperty of a human eotaxin. For example, as described in more detailbelow, some portions of a human eotaxin can be produced (e.g., syntheticpeptides) and used to produce antibodies. These portions are immunogenicand induce an antibody response against themselves when used in asuitable immunization protocol (e.g., conjugated to a suitable carrier).However, portions are not required to be immunogenic. As used herein, aportion (polypeptide or peptide) of human eotaxin having “at least oneimmunological property” of human eotaxin is a polypeptide or peptidewhich (a) is bound by at least one antibody of a selected epitopicspecificity which binds a naturally occurring human eotaxin; and/or (b)is an immunogen capable of inducing the formation in a suitable animalof at least one antibody of a selected epitopic specificity which bindsa naturally occurring human eotaxin. For example, a portion can becross-reactive with an antibody which is raised against and/or reactivewith human eotaxin. In a preferred embodiment, the antibody of selectedepitopic specificity is specific for human eotaxin, and in aparticularly preferred embodiment binds to human eotaxin with highaffinity (e.g., a Ka in the range of about 1-10 nM).

In yet another embodiment, an isolated and/or recombinant portion ofhuman eotaxin has at least one function characteristic of human eotaxinand at least one immunological property of a human eotaxin.

Studies on the structure and function of C—C chemokines provide thebasis for being able to divide C—C chemokines into functional domains(e.g., leader peptide, mature protein; Miller, M. D. and M. S. Krangel,Critical Rev. Immunol., 12 (1,2): 17-46 (1992); see also, Gong, J. H.and I. L. Clark-Lewis, J. Exp. Med., 181: 631-6410 (1995)). Portions ofhuman eotaxin can be produced which have full or partial function ontheir own, or which when joined with another portion of a secondchemokine (though fully, partially, or nonfunctional alone), constitutea functional protein having at least one function characteristic of amammalian C—C chemokine, such as human eotaxin (e.g., binding, leukocyteactivation and/or stimulation function).

The invention further relates to mutants, variants or derivatives of ahuman eotaxin (e.g., a mature human eotaxin). Such variants includenatural or artificial variants of a naturally occurring human eotaxin,differing by the addition, deletion or substitution of one or more aminoacid residues, or modified polypeptides in which one or more residues ismodified, and mutants comprising one or more modified residues.

The invention further relates to fusion proteins, comprising a humaneotaxin (e.g., mature human eotaxin, or the full-length product (aminoacids 1-97 of FIG. 2)) as a first moiety, linked to a second moiety notoccurring in the human eotaxin as found in nature. Thus, the secondmoiety can be an amino acid or polypeptide. The first moiety can be inan N-terminal location, C-terminal location or internal to the fusionprotein. In one embodiment, the fusion protein comprises a human eotaxinor portion thereof as the first moiety, and a second moiety comprising alinker sequence and affinity ligand (e.g., an enzyme, an antigen,epitope tag).

Fusion proteins can be produced by a variety of methods. For example,some embodiments can be produced by the insertion of a human eotaxingene or portion thereof into a suitable expression vector, such asBluescript®II SK+/− (Stratagene), pGEX-4T-2 (Pharmacia) and pET-15b(Novagen). The resulting construct is then introduced into a suitablehost cell for expression. Upon expression, fusion protein can beisolated or purified from a cell lysate by means of a suitable affinitymatrix (see e.g., Current Protocols in Molecular Biology (Ausubel, F. M.et al., eds., Vol. 2, Suppl. 26, pp. 16.4.1-16.7.8 (1991)). In addition,affinity labels provide a means of detecting a fusion protein comprisinga human eotaxin moiety. For example, the cell surface expression orpresence in a particular cell fraction of a fusion protein comprising anantigen or epitope affinity label can be detected by means of anappropriate antibody.

Nucleic Acids, Constructs and Vectors

The present invention further relates to isolated and/or recombinant(including, e.g., essentially pure) nucleic acids having sequences whichencode a protein of the present invention, including human eotaxin or aportion thereof. In one embodiment, the nucleic acid or portion thereofencodes a protein having at least one function characteristic of humaneotaxin, such as a binding function (e.g., binding to an eotaxinreceptor or other receptor); a leukocyte activation function (e.g.,activation of a G protein, induction of rapid and transient increase inthe concentration of cytosolic free calcium [Ca²⁺]_(i), induction ofexocytosis or inflammatory mediator release, leukocyte integrinupregulation and/or activation); and/or a leukocyte stimulation function(e.g., induces accumulation and/or chemotaxis of leukocytes, especiallyof eosinophils such as human or primate eosinophils (haseosinophil-specific chemoattractant activity)). The present inventionalso relates more specifically to isolated and/or recombinant nucleicacids comprising sequences which encode a human eotaxin or a portionthereof.

The invention further relates to isolated and/or recombinant nucleicacids that are characterized by (1) their ability to hybridize to: (a) anucleic acid having the sequence shown in FIG. 1A-1B (SEQ ID NO:1) orFIG. 2 (SEQ ID NO:3), (b) the complement of the sequence shown in FIG.1A-1B (SEQ ID NO:1) or FIG. 2 (SEQ ID NO:3), (c) the RNA counterpart ofeither of the foregoing, wherein U is substituted for T, or (d) aportion of any of the foregoing (e.g., a portion comprising the openreading frame); or (2) by their ability to encode a polypeptide havingthe amino acid sequence shown in FIG. 1A-1B (SEQ ID NO:2) or FIG. 2 (SEQID NO:4) or a functional equivalent thereof (i.e., a polypeptide whichbinds one or more natural receptors of human eotaxin and/or inducesaccumulation and/or chemotaxis of leukocytes, especially of eosinophilssuch as human or primate eosinophils); or (3) by both characteristics.

C—C chemokine genes typically encode a polypeptide having anamino-terminal signal sequence or presequence for secretion, which iscleaved to yield a mature protein active in binding, and in inducingaccumulation and/or chemotaxis. Alignment of the amino acid sequence ofthe protein encoded by the genomic and cDNA clones described herein withother C—C chemokines indicates that the encoded protein also has aleader sequence for secretion. Based on the alignment with other C—Cchemokines, the leader sequence corresponds to amino acids 1-23 of thepredicted protein, yielding a predicted mature protein beginning withGly²⁴ (amino acids 24-97 of FIG. 1A-1B (SEQ ID NO:2) or FIG. 2 (SEQ IDNO:4)). Functional equivalents of a polypeptide having the amino acidsequence shown in FIG. 1A-1B (SEQ ID NO:2) or FIG. 2 (SEQ ID NO:4)include proteins corresponding to mature eotaxin. In one embodiment,functional equivalents of the amino acid sequence shown in FIG. 1A-1B(SEQ ID NO:2) or FIG. 2 (SEQ ID NO:4) are defined by their sequencesimilarity to a protein having an amino acid sequence corresponding toamino acids 24-97 of FIG. 1A-1B (amino acids 24-97 of SEQ ID NO:2) orFIG. 2 (SEQ ID NO:4), and the functional equivalents have at least about75% (≧75%) sequence similarity with said protein. In a preferredembodiment, the functional equivalents share at least about 80% sequencesimilarity with said protein. More preferably, the percent amino acidsequence similarity is at least about 90%, and still more preferably, atleast about 95%.

Isolated and/or recombinant nucleic acids meeting these criteriacomprise nucleic acids having sequences identical to sequences ofnaturally occurring human eotaxin genes (including polymorphic orallelic variants) and portions thereof, or variants of the naturallyoccurring sequences. Such variants include mutants differing by theaddition, deletion or substitution of one or more residues, modifiednucleic acids in which one or more residues is modified (e.g., DNA orRNA analogs), and mutants comprising one or more modified residues.

Such nucleic acids can be detected and isolated by hybridization underhigh stringency conditions or moderate stringency conditions, forexample. “High stringency conditions” and “moderate stringencyconditions” for nucleic acid hybridizations are explained on pages2.10.1-2.10.16 (see particularly 2.10.8-11) and pages 6.3.1-6 in CurrentProtocols in Molecular Biology (Ausubel, F. M. et al., eds., Vol. 1,Suppl. 26, 1991), the teachings of which are incorporated herein byreference (see also Example 2). Factors such as probe length, basecomposition, percent mismatch between the hybridizing sequences,temperature and ionic strength influence the stability of nucleic acidhybrids. Thus, high or moderate stringency conditions can be determinedempirically, depending in part upon the characteristics of the known DNAto which other nucleic acids are being compared for homology.

Isolated and/or recombinant nucleic acids that are characterized bytheir ability to hybridize to a nucleic acid having the sequence shownin FIG. 1A-1B (SEQ ID NO:1) or FIG. 2 (SEQ ID NO:3), the complement orRNA counterpart of the sequence shown in FIG. 1A-1B (SEQ ID NO:1) orFIG. 2 (SEQ ID NO:3), or a portion thereof (e.g., under high conditions)can further encode a human eotaxin or portion thereof. Such portionshave at least one function characteristic of human eotaxin, such as abinding function (e.g., binding to an eotaxin receptor or otherreceptor); a leukocyte activation function (e.g., activation of a Gprotein, induction of rapid and transient increase in the concentrationof cytosolic free calcium [Ca²⁺]_(i), induction of exocytosis orinflammatory mediator release, leukocyte integrin activation); and/or aleukocyte stimulation function (e.g., induces accumulation and/orchemotaxis of leukocytes, especially of eosinophils), and/or at leastone immunological property of a human eotaxin.

The binding function of a polypeptide encoded by hybridizing nucleicacid can be detected in binding or binding inhibition assays usingmembrane fractions containing a suitable receptor or cells expressingreceptor, for instance (see Examples 6 and 7; see also, Van Riper etal., J. Exp. Med., 177: 851-856 (1993); Sledziewski et al., U.S. Pat.No. 5,284,746 (Feb. 8, 1994)). Thus, the ability of the encoded proteinor polypeptide to bind a receptor present on eosinophils or cellstransfected with a suitable receptor, such as C—C CKR-3, can beassessed.

The leukocyte activation function of a protein or polypeptide encoded byhybridizing nucleic acid can be detected by enzymatic assays for Gprotein activity responsive to polypeptide binding to a receptor (e.g.,exchange of GTP for GDP on the G protein α subunit, using membranefractions). G protein coupling can be further assessed, for example,using assays in which stimulation by G protein is blocked by treatmentor pre-treatment of cells or a suitable cellular fraction (e.g.,membranes) with specific inhibitors of G proteins, such as Bordetellapertussis toxin (Bischoff, S. C. et al., Eur. J. Immunol. 23: 761-767(1993); Sozzani, S. et al., J. Immunol. 147: 2215-2221 (1991)).

Standard assays which monitor the induction of a rapid and transientincrease in the concentration of cytosolic free calcium [Ca²⁺]_(i)(Example 5), exocytosis (e.g., of enzymes such as eosinophil peroxidase,β-glucuronidase) or inflammatory mediator (e.g., histamine, leukotriene)release can be used to assess the response of leukocytes to a humaneotaxin, variant or portion thereof (see e.g., Bischoff, S. C. et al.,Eur. J. Immunol., 23: 761-767 (1993); Rot, A. et al., J. Exp. Med., 176:1489-1495 (1992); Baggliolini, M. and C. A. Dahinden, Immunology Today,15:127-133 (1994) and references cited therein).

The stimulatory function of a protein or polypeptide encoded byhybridizing nucleic acid can be detected by standard assays forchemotaxis. For example, chemotaxis of eosinophils in response to apolypeptide can be assessed (see e.g., Example 4). In anotherembodiment, the chemotaxis of cells expressing an eotaxin receptor inresponse to a polypeptide is monitored (see e.g., Example 7).

Functions characteristic of a human eotaxin may also be assessed byother suitable methods (see below). These methods, alone or incombination with other suitable methods can also be used in proceduresfor the identification and/or isolation of nucleic acids which encode apolypeptide having the amino acid sequence shown in FIG. 1A-1B (SEQ IDNO:2) or FIG. 2 (SEQ ID NO:4) or functional equivalents thereof, andhaving an activity detected by the assay. Portions of isolated and/orrecombinant nucleic acids which encode polypeptide portions of theprotein shown in FIG. 1A-1B (SEQ ID NO:2) or FIG. 2 (SEQ ID NO:4) havinga certain function can be also identified and isolated in this manner.

Nucleic acids of the present invention can be used in the production ofproteins or polypeptides. For example, a nucleic acid containing all orpart of the coding sequence for a human eotaxin or a variant thereof, orDNA which hybridizes to the nucleic acid sequence shown in FIG. 1A-1B(SEQ ID NO:1) or FIG. 2 (SEQ ID NO:3) (or to the complement or RNAcounterpart of these sequences), can be incorporated into variousconstructs and vectors created for further manipulation of sequences orfor production of the encoded polypeptide in suitable host cells.

Nucleic acids referred to herein as “isolated” are nucleic acidsseparated away from the nucleic acids of the genomic DNA or cellular RNAof their source of origin (e.g., as it exists in cells or in a mixtureof nucleic acids such as a library), and may have undergone furtherprocessing. “Isolated” nucleic acids include nucleic acids obtained bymethods described herein, similar methods or other suitable methods,including essentially pure nucleic acids, nucleic acids produced bychemical synthesis, by combinations of biological and chemical methods,and recombinant nucleic acids which are isolated (see e.g., Daugherty,B. L. et al., Nucleic Acids Res., 19(9):2471-2476 (1991); Lewis, A. P.and J. S. Crowe, Gene, 101: 297-302 (1991)). Nucleic acids referred toherein as “recombinant” are nucleic acids which have been produced byrecombinant DNA methodology, including those nucleic acids that aregenerated by procedures which rely upon a method of artificialrecombination, such as the polymerase chain reaction (PCR) and/orcloning into a vector using restriction enzymes. “Recombinant” nucleicacids are also those that result from recombination events that occurthrough the natural mechanisms of cells, but are selected for after theintroduction to the cells of nucleic acids designed to allow and makeprobable a desired recombination event.

Antisense Constructs

In another embodiment, the nucleic acid is an antisense nucleic acid,which is complementary, in whole or in part, to a target moleculecomprising a sense strand, and can hybridize with the target molecule.The target can be DNA, or its RNA counterpart (i.e., wherein T residuesof the DNA are U residues in the RNA counterpart). When introduced intoa cell using methods known in the art or other suitable methods,antisense nucleic acid can inhibit the expression of the gene encoded bythe sense strand. Antisense nucleic acids can be produced by standardtechniques.

In one embodiment, the antisense nucleic acid is wholly or partiallycomplementary to and can hybridize with a target nucleic acid, whereinthe target nucleic acid can hybridize to a nucleic acid having thesequence of the complement of the nucleic acid shown in FIG. 1A-1B (SEQID NO:1) or FIG. 2 (SEQ ID NO:3). For example, antisense nucleic acidcan be complementary to a target nucleic acid having the sequence ofFIG. 1A-1B (SEQ ID NO:1) or a portion thereof sufficient to allowhybridization. In another embodiment, the antisense nucleic acid iswholly or partially complementary to and can hybridize with a targetnucleic acid which encodes, for example, human eotaxin.

Antisense nucleic acids are useful for a variety of purposes, includingresearch and therapeutic applications. For example, a constructcomprising an antisense nucleic acid can be introduced into a suitablecell to inhibit eotaxin expression. In one embodiment, such a constructis introduced into some or all of the cells of a mammal. The antisensenucleic acid inhibits eotaxin expression, and inflammatory processesmediated by eotaxin can be inhibited. Thus, an inflammatory disease orcondition can be treated using an antisense nucleic acid of the presentinvention. Suitable laboratory animals comprising an antisense constructcan also provide useful models for deficiencies of leukocyte function,and of eosinophil deficiency in particular, and provide furtherinformation regarding eotaxin function. Such animals can providevaluable models of infectious disease, useful for elucidating the roleof leukocytes, such as eosinophils, in host defenses.

Novel Chemokine Genes

Because advances in the understanding and treatment of humaninflammatory and autoimmune diseases and of parasitic infections wouldbe of tremendous benefit, human eotaxin was the species selected for theexperimental work described herein. However, the approaches described toisolate and manipulate genomic DNA and cDNA encoding a human eotaxin, toconstruct vectors and host strains, and to produce and use eotaxin orportions thereof, can be applied to other primates (e.g., a primateother than a human, such as a monkey (e.g., cynomolgus monkey)). Thehuman cDNA or genomic clones described herein, or sufficient portionsthereof, whether isolated and/or recombinant or synthetic, includingfragments produced by PCR, can be used as probes or primers to detectand/or recover allelic variants of the genes described herein, eotaxinhomologs or other related chemokine genes (e.g., novel C—C chemokinegenes) from other mammalian species (e.g., by hybridization, PCR orother suitable techniques). This can be achieved using the proceduresdescribed herein or other suitable methods.

Method of Producing Recombinant Proteins

Another aspect of the invention relates to a method of producing humaneotaxin or a portion thereof, and variants of human eotaxin. Example 3describes the chemical synthesis of a predicted mature human eotaxinconsisting of amino acids 24-97 of FIG. 2 (amino acids 24-97 of SEQ IDNO:4). In addition, constructs suitable for the expression of a humaneotaxin or a portion thereof are provided. The constructs can beintroduced into a suitable host cell. Cells expressing a recombinanthuman eotaxin, portion thereof, or variants of human eotaxin, can beproduced and maintained in culture. Such cells are useful for a varietyof purposes such as the production of protein for characterization,isolation and/or purification. Suitable host cells can be procaryotic,including bacterial cells such as E. coli, B. subtilis and/or othersuitable bacteria, or eucaryotic, such as fungal or yeast cells (e.g.,Pichia pastoris, Aspergillus species, Saccharomyces cerevisiae,Schizosaccharomyces pombe, Neurospora crassa), or other lower eucaryoticcells, and cells of higher eucaryotes such as those from insects (e.g.,Sf9 insect cells) or mammals (e.g., 293 cells, Chinese hamster ovarycells (CHO)). (See, e.g., Ausubel, F. M. et al., eds. Current Protocolsin Molecular Biology, Greene Publishing Associates and John Wiley & SonsInc., (1993)). In one embodiment, host cells capable of secreting amature protein are used.

Host cells which produce a recombinant human eotaxin, portion thereof,variant, or fusion protein can be produced as follows. For example, anucleic acid encoding all or part of the coding sequence for a humaneotaxin or fusion protein can be inserted into a nucleic acid vector,e.g., a DNA vector, such as a plasmid, virus or other suitable repliconfor expression. A variety of vectors are available, including vectorswhich are maintained in single copy or multiple copy, or which becomeintegrated into the host cell chromosome.

The transcriptional and/or translational signals of a human eotaxin genecan be used to direct expression. Alternatively, suitable expressionvectors are available. Suitable vectors for expression of a nucleic acidencoding all or part of the coding sequence, for e.g., a human eotaxin,portion thereof, or variant of human eotaxin can contain a number ofadditional components, including, but not limited to one or more of thefollowing: an origin of replication; a selectable marker gene; one ormore expression control elements, such as a transcriptional controlelement (e.g., a promoter, an enhancer, terminator), and/or one or moretranslation signals; a signal sequence or leader sequence of humanorigin or from a heterologous species (for secretion provided by thevector, eotaxin coding sequence, or other source).

A promoter is provided for expression in a suitable host cell. Promoterscan be constitutive or inducible. In the vectors, the promoter isoperably linked to a nucleic acid encoding the human eotaxin, portionthereof or variant, and is capable of directing expression of theencoded polypeptide. A variety of suitable promoters for procaryotic(e.g., lac, tac, T3, T7 promoters for E. coli) and eucaryotic (e.g.,yeast alcohol dehydrogenase (ADH1), SV40, CMV) hosts are available.

In addition, the expression vectors typically comprise a selectablemarker for selection of host cells carrying the vector, in the case ofreplicable expression vectors, an origin or replication. Genes encodingproducts which confer antibiotic or drug resistance are commonselectable markers and may be used in procaryotic (e.g., β-lactamasegene (ampicillin resistance), Tet gene for tetracycline resistance) andeucaryotic cells (e.g., neomycin (G418 or geneticin), gpt (mycophenolicacid), ampicillin, or hygromycin resistance genes). Dihydrofolatereductase marker genes permit selection with methotrexate in a varietyof hosts. Genes encoding the gene product of auxotrophic markers of thehost (e.g., LEU2, URA3, HIS3) are often used as selectable markers inyeast. Use of viral (e.g., baculovirus) or phage vectors, and vectorswhich are capable of integrating into the genome of the host cell, suchas retroviral vectors, are also contemplated. The present invention alsorelates to cells carrying these expression vectors.

When the nucleic acid encoding the human eotaxin, portion thereof, orvariant is inserted into the vector, operably linked to one or more ofthese expression control elements, and the resulting construct isintroduced into host cells maintained under conditions suitable forexpression, the encoded polypeptide is produced. The construct can beintroduced into cells by a method appropriate to the host cell selected(e.g., transformation, transfection, electroporation, infection). Forproduction of a human eotaxin, host cells comprising the construct aremaintained under conditions appropriate for expression, (e.g., in thepresence of inducer, suitable media supplemented with appropriate salts,growth factors, antibiotic, nutritional supplements, etc.). The encodedprotein (e.g., human eotaxin) can be isolated from the host cells ormedium.

Antibodies

The invention further relates to antibodies reactive with a humaneotaxin or portion thereof. In one embodiment, antibodies are raisedagainst an isolated and/or recombinant protein of the present invention,including human eotaxin or a portion thereof (e.g., a peptide). In apreferred embodiment, the antibodies specifically bind a human eotaxinor a portion thereof.

The antibodies of the present invention can be polyclonal or monoclonal(see e.g., Example 8), and the term antibody is intended to encompassboth polyclonal and monoclonal antibodies. Antibodies of the presentinvention can be raised against an appropriate immunogen, includingproteins or polypeptides of the present invention, such as an isolated(e.g., synthetic) and/or recombinant human eotaxin or a portion thereof(e.g., synthetic peptides). Synthetic peptides can be conjugated to asuitable carrier for immunization.

Preparation of Immunizing Antigen, and Polyclonal and MonoclonalAntibody production can be performed using any suitable technique. Avariety of methods have been described (see e.g., Kohler et al., Nature,256: 495-497 (1975) and Eur. J. Immunol. 6: 511-519 (1976); Milstein etal., Nature 266: 550-552 (1977); Koprowski et al., U.S. Pat. No.4,172,124; Harlow, E. and D. Lane, 1988, Antibodies: A LaboratoryManual, (Cold Spring Harbor Laboratory: Cold Spring Harbor, N.Y.);Current Protocols In Molecular Biology, Vol. 2 (Supplement 27, Summer'94), Ausubel, F. M. et al., Eds., (John Wiley & Sons: New York, N.Y.),Chapter 11, (1991)). Generally, a hybridoma is produced by fusing asuitable immortal cell line (e.g., a myeloma cell line such as SP2/0)with antibody producing cells. The antibody producing cell, preferablythose of the spleen or lymph nodes, are obtained from animals immunizedwith the antigen of interest. The fused cells (hybridomas) are isolatedusing selective culture conditions, and cloned by limiting dilution.Cells which produce antibodies with the desired specificity are selectedby a suitable assay (e.g., ELISA).

Single chain antibodies, and chimeric, humanized or primatized(CDR-grafted) antibodies, as well as chimeric or CDR-grafted singlechain antibodies, comprising portions derived from different species,are also encompassed by the present invention and the term “antibody”.The various portions of these antibodies can be joined togetherchemically by conventional techniques, or can be prepared as acontiguous protein using genetic engineering techniques. For example,nucleic acids encoding a chimeric or humanized chain can be expressed toproduce a contiguous protein. See, e.g., Cabilly et al., U.S. Pat. No.4,816,567; Cabilly et al., European Patent No. 0,125,023 B1; Boss etal., U.S. Pat. No. 4,816,397; Boss et al., European Patent No. 0,120,694B1; Neuberger, M. S. et al., WO 86/01533; Neuberger, M. S. et al.,European Patent No. 0,194,276 B1; Winter, U.S. Pat. No. 5,225,539; andWinter, European Patent No. 0,239,400 B1. See also, Newman, R. et al.,BioTechnology, 10: 1455-1460 (1992), regarding primatized antibody, andLadner et al., U.S. Pat. No. 4,946,778 and Bird, R. E. et al., Science,242: 423-426 (1988)) regarding single chain antibodies.

In addition, functional fragments of antibodies, including fragments ofchimeric, humanized, primatized or single chain antibodies, can also beproduced. Functional fragments of foregoing antibodies retain at leastone binding function and/or modulation function of the full-lengthantibody from which they are derived. For example, antibody fragmentscapable of binding to a human eotaxin or portion thereof, including, butnot limited to, Fv, Fab, Fab′ and F(ab′)₂ fragments are encompassed bythe invention. Such fragments can be produced by enzymatic cleavage orby recombinant techniques. For instance, papain or pepsin cleavage cangenerate Fab or F(ab′)₂ fragments, respectively. Alternatively,antibodies can be produced in a variety of truncated forms usingantibody genes in which one or more stop codons has been introducedupstream of the natural stop site. For example, a chimeric gene encodinga F(ab′)₂ heavy chain portion can be designed to include DNA sequencesencoding the CH₁ domain and hinge region of the heavy chain.

The antibodies of the present invention are useful in a variety ofapplications, including processes, research, diagnostic and therapeuticapplications. For instance, they can be used to isolate and/or purifyhuman eotaxin, portions thereof, or variants of human eotaxin, and tostudy human eotaxin structure (e.g., conformation) and function.

The antibodies of the present invention can also be used to modulatechemokine function in in vitro and therapeutic applications. Forinstance, antibodies can act as inhibitors to inhibit (reduce orprevent) (a) binding of a human eotaxin, inhibitor or promoter ofeotaxin function, for example, to its receptor(s), (b) leukocyteactivation, (c) and/or leukocyte stimulation (e.g., accumulation and/orchemotaxis of leukocytes such as eosinophils). Antibodies which act asinhibitors of human eotaxin function can block human eotaxin bindingdirectly or indirectly (e.g., by causing a conformational change or bydesensitization (with or without inhibition of binding of a ligand)).

In addition, the various antibodies of the present invention can be usedto detect or measure the expression of eotaxin, for example, in cellstransfected with a nucleic acid of the present invention or in a samplefrom a patient (e.g., inflammatory exudate). Thus, they also haveutility in diagnostic or in vitro applications.

Anti-idiotypic antibodies are also provided. Anti-idiotypic antibodiesrecognize antigenic determinants associated with the antigen-bindingsite of another antibody. Anti-idiotypic antibodies can be preparedagainst a second antibody by immunizing an animal of the same species,and preferably of the same strain, as the animal used to produce thesecond antibody. See e.g., U.S. Pat. No. 4,699,880.

In one embodiment, antibodies are raised against a human eotaxin or aportion thereof, and these antibodies are used in turn to produce ananti-idiotypic antibody. This anti-Id antibody can bind molecules whichbind eotaxin, such as a receptor(s) for eotaxin, and can be used in animmunoassay to detect, isolate and/or quantitate molecules which bindeotaxin. In one embodiment, such an anti-idiotypic antibody can be aninhibitor of eotaxin function, although it does not bind eotaxin itself.In another embodiment, such an anti-idiotypic antibody can be an agonistof eotaxin function, by binding to one or more natural receptors ofhuman eotaxin and/or inducing leukocyte activation (e.g., activation ofa G protein, induction of rapid and transient increase in theconcentration of cytosolic free calcium [Ca²⁺]_(i), induction ofexocytosis or inflammatory mediator release, leukocyte integrinactivation) and/or leukocyte stimulation (e.g., induce accumulationand/or chemotaxis of leukocytes, especially of eosinophils).

Anti-idiotypic (i.e., Anti-Id) antibody can itself be used to raise ananti-idiotypic antibody (i.e., Anti-anti-Id). Such an antibody can besimilar or identical in specificity to the original immunizing antibody.In one embodiment, antibody antagonists which block binding to receptorcan be used to raise Anti-Id, and the Anti-Id can be used to raiseAnti-anti-Id, which can have a specificity which is similar or identicalto that of the antibody antagonist. These anti-anti-Id antibodies can beassessed for inhibitory effect on eotaxin function to determine if theyare antagonists.

Single chain, and chimeric, humanized or primatized (CDR-grafted), aswell as chimeric or CDR-grafted single chain anti-idiotypic antibodiescan be prepared, and are encompassed by the term anti-idiotypicantibody. Antibody fragments of such antibodies can also be prepared.

Identification of Inhibitors or Promoters of Human Eotaxin Function andIdentification of Receptors for Eotaxin

As used herein, a ligand is a substance which binds to a receptorprotein. For example, human eotaxin binds to an eotaxin receptor. In oneembodiment, eotaxin can bind selectively to two or more receptors. In apreferred embodiment, eotaxin binding of a receptor occurs with highaffinity. The term ligand refers to substances including, but notlimited to, a natural ligand, whether isolated and/or purified,synthetic, and/or recombinant, a homolog of a natural ligand (e.g., fromanother mammal), antibodies, portions of such molecules, and othersubstances which bind receptor. A natural ligand of a selected receptorcan bind to the receptor under physiological conditions, and is of anorigin (species) which is the same as that of the receptor. The termligand encompasses substances which are inhibitors or promoters ofreceptor activity, as well as substances which bind but lack inhibitoror promoter activity.

As used herein, an inhibitor is a substance which inhibits at least onefunction characteristic of a human eotaxin, such as a binding function(e.g., binding to an eotaxin receptor or other receptor); a leukocyteactivation function (e.g., activation of a G protein, induction of rapidand transient increase in the concentration of cytosolic free calcium[Ca²⁺]_(i), induction of exocytosis or inflammatory mediator release,leukocyte integrin upregulation and/or activation); and/or a leukocytestimulation function (e.g., induces accumulation and/or chemotaxis ofleukocytes, especially of eosinophils such as human or primateeosinophils). The term inhibitor refers to substances includingantagonists, which can bind an eotaxin receptor and inhibit eotaxinfunction (e.g., binding function, leukocyte activation and/orstimulation function is inhibited) directly or indirectly, such as acompetitive inhibitor of eotaxin binding to its receptor(s) (e.g., afragment of naturally occurring human eotaxin or a variant of a humaneotaxin) or an anti-idiotypic antibody which binds a receptor(s) foreotaxin. In one embodiment, the inhibitor is a substance other thannaturally occurring human eotaxin or a polypeptide having the same aminoacid sequence as naturally occurring human eotaxin, or other naturallyoccurring ligands of a human eotaxin receptor (e.g., RANTES is anotherligand for CKR-3 receptor protein). The term inhibitor also encompassesagents which inhibit (prevent or reduce (e.g., decrease or abolish))production, release or activity of human eotaxin, such as ananti-eotaxin antibody which inhibits eotaxin function, or other agent.

As used herein, a promoter is a substance which promotes (induces orenhances) at least one function characteristic of a human eotaxin, suchas a binding function, leukocyte (e.g., eosinophil) activation functionand/or leukocyte (e.g., eosinophil) stimulation function. The termpromoter refers to substances including agonists such as ananti-idiotypic antibody as described herein, variants of human eotaxin,a homolog of eotaxin isolated from another species, and substances whichpromote or enhance eotaxin function.

Because of the role of chemokines in the selective induction ofleukocyte chemotaxis and leukocyte activation in response tochemoattractants, chemokines play a fundamental role in leukocytemigration, and particularly in migration associated with inflammation.Chemokines, produced at sites of inflammation and infection (e.g.,wounds), specifically recruit selected leukocyte subtypes from thecirculation to the site of inflammation in the tissues. Subsequent tochemokine binding to a leukocyte chemokine receptor, integrin activationoccurs, and leukocytes adhere firmly to the endothelial cell wall vialeukocyte integrins and endothelial cell adhesion molecules. Theleukocytes become flat in shape, and migrate through the endotheliumtowards sites of inflammation in the tissues. The specificity of aleukocyte for a tissue or inflammatory site is, in many cases,determined at the level of the chemokine-receptor interaction, ratherthan at the level of the adhesion interaction between integrin andcellular adhesion molecules.

Modulation of eotaxin function according to the present invention,through the inhibition or promotion of human eotaxin function (e.g.,binding, activation and/or stimulation), provides an effective andselective way of inhibiting or promoting leukocyte-mediated inflammatoryaction, particularly that of eosinophils. Inhibitors and promoters ofeotaxin function, such as those identified as described herein, can beused to modulate leukocyte function for therapeutic and/or prophylacticpurposes in humans. As a major eosinophil chemokine, human eotaxin is animportant target for interfering with or promoting leukocyte, especiallyeosinophil function. Agents which inhibit or promote human eotaxinfunction (e.g., binding to a receptor(s)), such as other ligands of aneotaxin receptor, inhibitors and promoters identified according to thepresent method, are particularly useful for modulating eosinophilfunction for therapeutic and/or prophylactic purposes. It will beappreciated that inhibitors or promoters of human eotaxin, can also beinhibitors or promoters of primate eotaxins or other mammalian eotaxinhomologs.

The assays described below, which rely upon the nucleic acids andproteins of the present invention, can be used, alone or in combinationwith each other or other suitable methods, to identify inhibitors orpromoters of eotaxin function. The in vitro method of the presentinvention can be used in high-throughput screening. These assays can beadapted for processing large numbers of samples (e.g., a 96 wellformat).

In another aspect, they can be used to identify receptors for eotaxin,which are also useful in identifying inhibitors or promoters of humaneotaxin. For example, the present invention also relates to theidentification of a receptor-ligand pair: human eotaxin and human C—Cchemokine receptor 3 (CKR-3). As shown herein, human eosinophils have asingle class of high affinity binding sites for eotaxin. As described incopending U.S. Ser. No. 08/375,199, entitled “Novel G Protein-CoupledReceptor Gene and Methods of Use Therefor”, filed Jan. 19, 1995, humaneosinophils express CKR-3 receptors. As further shown herein, synthetichuman eotaxin (Example 3) was shown to bind to cells which aretransfected with a gene encoding a human C—C chemokine receptor-3 (FIG.11), and to induce chemotaxis in response to binding (FIGS. 12A-12E).U.S. Ser. No. 08/375,199 describes mammalian C—C CKR-3 genes, such ashuman CKR-3 genes, which can be made (e.g., by isolating the gene usingPCR or by other suitable methods) based on the sequence shown in FIG.15A-15D.

In one embodiment, an isolated eotaxin receptor gene from, e.g., amammal, is incorporated into an expression system to produce a receptorprotein or polypeptide (essentially as described above for eotaxin). Anisolated and/or recombinant eotaxin receptor, such as a receptorexpressed in cells stably or transiently transfected with a constructcomprising a nucleic acid which encodes an eotaxin receptor, or presentin a cell fraction (e.g., membrane fraction from transfected cells, orfurther purified if desired) containing receptor, can be used in testsfor eotaxin function and/or to identify inhibitors or promoters ofeotaxin in vitro or in vivo.

For example, isolated and/or recombinant human C—C chemokine receptor 3(CKR-3) gene, such as the gene illustrated in FIG. 15A-15D, can be usedin the present method. The effect of an agent is assessed by monitoringreceptor function as described herein or using other suitabletechniques. For example, stable or transient transfectants, such asstable tranfectants of mouse L1-2 pre-B cells (see e.g., Example 7) orinsect cells (e.g., Sf9 cells) infected with a baculovirus vectorcomprising a nucleic acid encoding receptor can be used in bindingassays. Stable transfectants of mouse L1-2 pre-B cells or of othersuitable cells capable of chemotaxis can be used in chemotaxis assays,for example.

According to the method of the present invention, agents can beindividually screened or one or more agents can be testedsimultaneously. Where a mixture of compounds is tested, the agent(s)selected by the processes described can be separated (as appropriate)and identified by suitable methods (e.g., PCR, sequencing,chromatography). The presence of one or more agents (e.g., an inhibitor,promoter) in a test sample can also be determined according to thesemethods.

Combinatorial libraries of compounds (e.g., organic compounds,recombinant or synthetic peptides, “peptoids”, nucleic acids) producedby combinatorial chemical synthesis or other methods can be tested (seee.g., Zuckerman, R. N. et al., J. Med. Chem., 37: 2678-2685 (1994) andreferences cited therein; see also, Ohlmeyer, M. H. J. et al., Proc.Natl. Acad. Sci. USA, 90:10922-10926 (1993) and DeWitt, S. H. et al.,Proc. Natl. Acad. Sci. USA, 90:6909-6913 (1993), relating to taggedcompounds; Rutter, W. J. et al. U.S. Pat. No. 5,010,175; Huebner, V. D.et al., U.S. Pat. No. 5,182,366; and Geysen, H. M., U.S. Pat. No.4,833,092). Where compounds selected from a combinatorial library by thepresent method carry unique tags, identification of individual compoundsby chromatographic methods is possible.

Other sources of potential inhibitors and/or promoters of eotaxininclude, but are not limited to, substances such as otherchemoattractants, such as a second human chemokine (e.g., RANTES,MCP-3), a chemokine from another mammal (e.g., for a human receptor, ahomolog of a human chemokine obtained from a non-human source); variantsof other chemoattractants or chemokines, such as naturally occurring,synthetic or recombinant variants; other mammalian (e.g., human) CKR-3receptor ligands, inhibitors and/or promoters (e.g., antibodies,antagonists, agonists), and variants thereof; other G-protein coupledreceptor ligands, inhibitors and/or promoters (e.g., antagonists oragonists); and soluble portions of a mammalian CKR-3 receptor, such as asuitable receptor peptide or analog which can inhibit receptor function(see e.g., Murphy, R. B., WO 94/05695).

Binding Assays

The isolated and/or recombinant proteins of the present invention (e.g.,synthetic predicted mature eotaxin, a fusion protein comprisingpredicted mature eotaxin) or portions thereof, can be used in a methodto select and/or identify agents or compounds which bind to or inhibitbinding of human eotaxin to an eotaxin receptor (e.g., human CKR-3receptor or other receptor present on leukocytes such as eosinophils)and which are potential inhibitors or promoters of human eotaxin. Agentsselected by the method, including ligands, inhibitors or promoters, canbe further assessed for an inhibitory or stimulatory effect on humaneotaxin function and/or for therapeutic utility.

In one embodiment, agents which bind to a mammalian (e.g., human)chemokine receptor protein that binds human eotaxin are identified bythe method. Binding function of proteins of the present invention suchas a human eotaxin, a portion thereof or variant of human eotaxin canalso be assessed in this manner. For example, an isolated and/orrecombinant chemokine receptor protein (e.g., CKR-3) can be maintainedunder conditions suitable for binding, the receptor is contacted with anagent to be tested or a protein of the present invention (e.g., humaneotaxin), and binding is detected or measured. In one embodiment,eosinophils expressing a (at least one type) receptor which binds humaneotaxin are used. In another embodiment, a receptor protein can beexpressed in cells stably or transiently transfected with a constructcomprising a nucleic acid sequence which encodes a receptor for eotaxin.The cells are maintained under conditions appropriate for expression ofreceptor, and are contacted with an agent or a protein of the presentinvention (e.g., human eotaxin, portion thereof, or a variant) underconditions suitable for eotaxin binding to receptor (e.g., in a suitablebinding buffer), and binding is detected by standard techniques. Tomeasure binding, the extent of binding can be determined relative to asuitable control (e.g., compared with background determined in theabsence of agent, compared with binding of a second agent (i.e., astandard), compared with binding of eotaxin to untransfected cells).Optionally, a cellular fraction, such as a membrane fraction, containingreceptor can be used in lieu of whole cells.

In one embodiment, the agent or protein of the present invention islabeled with a suitable label (e.g., fluorescent label, isotope label),and binding is determined by detection of the label. Specificity ofbinding can be assessed by competition or displacement, for example,using unlabeled agent, an unlabeled isolated and/or recombinant humaneotaxin, or a second ligand for receptor as competitor.

The binding activity of a promoter or inhibitor which binds receptor canbe assessed using such a ligand binding assay. Receptors of humaneotaxin, including human natural receptors or receptors from othermammalian species, can be identified in this manner.

Binding inhibition assays can also be used to identify inhibitors orpromoters which bind a chemokine receptor which binds human eotaxin, andwhich can inhibit or promote, respectively, at least one human eotaxinfunction. For example, a binding assay can be conducted in which areduction in the binding of isolated and/or recombinant human eotaxin(in the absence of an agent), as compared with binding of said humaneotaxin in the presence of the agent, is detected or measured. The agentcan be another protein of the present invention (e.g., a variant), forexample. A receptor (e.g., isolated and/or recombinant receptor, cellsbearing receptor or a membrane fraction containing receptor isolatedfrom such cells) can be contacted with the human eotaxin and the agentsimultaneously, or one after the other, in either order. A reduction inthe extent of binding of the human eotaxin in the presence of the agent,is indicative of inhibition of binding by the agent. For example,binding of eotaxin could be decreased or abolished.

In one embodiment, direct inhibition of the binding of a human eotaxinto a chemokine receptor by a second test agent is monitored. Forexample, the ability of an agent to inhibit the binding of ¹²⁵I-labeledeotaxin to human receptor (e.g., isolated receptor or receptor presenton cells) can be monitored. Such an assay can be conducted using eitherwhole cells (e.g., eosinophils, butyric acid-differentiated HL-60 cells,or a suitable cell line containing nucleic acid encoding a human C—Cchemokine receptor such as CKR-3 receptor) or a membrane fraction fromsaid cells, for instance.

Other methods of identifying an agent which binds a receptor which bindshuman eotaxin are available, such as methods which monitor events whichare triggered by receptor binding, including leukocyte activation and/orstimulation (See below).

Receptor-binding inhibitors (e.g., antagonists) and promoters (e.g.,agonists), which are identified in this manner, can be further assessedto determine whether, subsequent to binding, they act to inhibit oractivate other functions of human eotaxin and/or to assess theirtherapeutic utility.

Assays for Leukocyte Activation

The activation function of protein of the present invention or apromoter of human eotaxin function, such as an agonist, can be monitoredusing any suitable method. The binding of a human eotaxin or promoter ofhuman eotaxin function, such as an agonist, to a responsive receptor(e.g., a G protein-coupled receptor) can result in signalling, wherebythe activity of a G protein is stimulated. G protein activity, such ashydrolysis of GTP to GDP, or later events triggered by receptor binding,can be assayed by methods known in the art or other suitable methods(see e.g., Neote, K. et al., Cell, 72: 415-425 (1993); Van Riper et al.,J. Exp. Med., 177: 851-856 (1993); Dahinden, C. A. et al., J. Exp. Med.,179: 751-756 (1994); Sledziewski et al., U.S. Pat. No. 5,284,746).Activity in such an assay is indicative of activation function.

Standard assays which monitor the induction of a rapid and transientincrease in the concentration of intracellular (e.g., cytosolic) freecalcium [Ca²⁺]_(i) (Example 5), exocytosis (e.g., of enzymes such aseosinophil peroxidase, β-glucuronidase), or inflammatory mediatorrelease (e.g., histamine, leukotriene) can also be used to assess theresponse of leukocytes to a protein of the present invention (e.g.,isolated human eotaxin) or a promoter. In addition, leukocyte integrinupregulation and/or activation can also be monitored.

In another embodiment, these assays can be used to identify potentialinhibitors of eotaxin function. The inhibitory activity of an agent canbe determined using a human eotaxin in the assay, and assessing theability of an agent to inhibit the activity induced by eotaxin.

A protein of the present invention (e.g., a variant of human eotaxin)can also be screened for reduced ability (decreased ability or noability) to stimulate activity of a coupled G protein or to stimulate arapid and transient increase in the concentration of intracellular(cytosolic) free calcium [Ca²⁺]_(i), for instance. In this embodiment,although the protein has ligand binding activity (as determined byanother method in advance or later), engagement of the receptor does nottrigger or only weakly triggers activity of a coupled G protein. Suchagents are potential antagonists, and can be further assessed using asuitable assay. For instance, the same assay can be conducted in thepresence of an active human eotaxin, a portion thereof, or an activevariant of human eotaxin, and the ability of the agent to inhibit theactivity of a ligand or promoter is assessed.

Chemotaxis Assays and Assays of Leukocyte Stimulation

Chemotaxis assays can also be used to assess or measure function ofproteins of the present invention. These assays are based on thefunctional migration of cells in vitro or in vivo induced by a compound,and can be used to assess the binding and/or chemoattractant effect ofe.g., human eotaxin, inhibitors or promoters of human eotaxin function.The use of an in vitro transendothelial chemotaxis assay is described inExample 4 (see also FIG. 3). Springer et al. describe a transendotheliallymphocyte chemotaxis assay (Springer et al., WO 94/20142, publishedSep. 15, 1994, the teachings of which are incorporated herein byreference; see also Berman et al., Immunol Invest. 17: 625-677 (1988)).Migration across endothelium into collagen gels has also been described(Kavanaugh et al., J. Immunol, 146: 4149-4156 (1991)).

Suitable cells capable of chemotaxis, such as eosinophils, stabletransfectants of mouse L1-2 pre-B cells (or transfectants of othersuitable host cells capable of chemotaxis) can be used in chemotaxisassays. Cells which express a receptor which can bind and is responsiveto human eotaxin can also be incorporated into chemotaxis assays.

Generally, chemotaxis assays monitor the directional movement ormigration of a suitable cell (such as a leukocyte (e.g., lymphocyte,eosinophil, basophil)) into or through a barrier (e.g., endothelium, afilter), toward increased levels of a compound, from a first surface ofthe barrier toward an opposite second surface. Membranes or filtersprovide convenient barriers, such that the directional movement ormigration of a suitable cell into or through a filter, toward increasedlevels of a compound, from a first surface of the filter toward anopposite second surface of the filter, is monitored. In some assays, themembrane is coated with a substance to facilitate adhesion, such asICAM-1, fibronectin or collagen.

For example, one can detect or measure the migration of cells in asuitable container (a containing means), from a first chamber into orthrough a microporous membrane into a second chamber which contains acompound to be tested, and which is divided from the first chamber bythe membrane. A suitable membrane, having a suitable pore size formonitoring specific migration in response to compound, including, forexample, nitrocellulose, polycarbonate, is selected. For example, poresizes of about 3-8 microns, and preferably about 5-8 microns can beused. Pore size can be uniform on a filter or within a range of suitablepore sizes.

To assess migration, the distance of migration into the filter, thenumber of cells crossing the filter that remain adherent to the secondsurface of the filter, and/or the number of cells that accumulate in thesecond chamber can be determined using standard techniques (e.g.,microscopy). In one embodiment, the cells are labeled with a detectablelabel (e.g., radioisotope, fluorescent label, antigen or epitope label),and migration can be assessed by determining the presence of the labeladherent to the membrane and/or present in the second chamber using anappropriate method (e.g., by detecting radioactivity, fluorescence,immunoassay). The extent of migration induced by a compound can bedetermined relative to a suitable control (e.g., compared to backgroundmigration determined in the absence of the compound, to the extent ofmigration induced by a second compound (i.e., a standard), compared withmigration of untransfected cells induced by the compound).

Chambers can be formed from various solids, such as plastic, glass,polypropylene, polystyrene, etc. Membranes which are detachable from thechambers, such as a Biocoat (Collaborative Biomedical Products) orTranswell (Costar, Cambridge, Mass.) culture insert, facilitate countingadherent cells.

In the container, the filter is situated so as to be in contact withfluid containing cells in the first chamber, and the fluid in the secondchamber. Other than the test compound or additional ligand, inhibitor,or promoter present for the purpose of the assay, the fluid on eitherside of the membrane is preferably the same or substantially similar.The fluid in the chambers can comprise protein solutions (e.g., bovineserum albumin, fetal calf serum, human serum albumin) which may act toincrease stability and inhibit nonspecific binding of cells, and/orculture media.

In a preferred embodiment, particularly for eosinophils, lymphocytes, orother cells expressing an eotaxin receptor, transendothelial migrationis monitored. A transendothelial migration assay is preferred. Suchassays are better physiological models, because they more accuratelyrecapitulate in vivo conditions in which leukocytes emigrate from bloodvessels toward chemoattractants present in the tissues at sites ofinflammation by crossing the endothelial cell layer lining the vesselwall. In addition, transendothelial assays have lower background (signalto noise ratio).

In this embodiment, transmigration through an endothelial cell layer isassessed. To prepare the cell layer, endothelial cells can be culturedon a microporous filter or membrane, optionally coated with a substancesuch as collagen, fibronectin, or other extracellular matrix proteins,to facilitate the attachment of endothelial cells. Preferably,endothelial cells are cultured until a confluent monolayer is formed. Avariety of mammalian endothelial cells are available for monolayerformation, including for example, vein, artery or microvascularendothelium, such as human umbilical vein endothelial cells (CloneticsCorp., San Diego, Calif.) or a suitable cell line, such as the ECV 304cell line used in Example 4. To assay chemotaxis in response to aprotein of the present invention, endothelial cells of human origin orfrom a heterologous mammalian species or genus can also be used.

Generally, the assay is performed by detecting the directional migrationof cells into or through a membrane or filter, in a direction towardincreased levels of a compound, from a first surface of the filtertoward an opposite second surface of the filter, wherein the filtercontains an endothelial cell layer on a first surface. Directionalmigration occurs from the area adjacent to the first surface, into orthrough the membrane, towards a compound situated on the opposite sideof the filter. The concentration of compound present in the areaadjacent to the second surface, is greater than that in the areaadjacent to the first surface.

In one embodiment, a chemotaxis assay is used to test for ligand orpromoter activity of an agent. A composition comprising cells capable ofmigration and expressing suitable receptor are placed in the firstchamber, and a composition comprising the agent to be tested (e.g., ahuman eotaxin or other compound) is placed in the second chamber,preferably in the absence of other ligands or promoters capable ofinducing chemotaxis of the cells in the first chamber (havingchemoattractant function). However, one or more ligands or promotershaving chemoattractant function may be present. Compounds which can bindreceptor and induce chemotaxis of the cells expressing an eotaxinreceptor in this assay are ligands or promoters of receptor function. Itwill be apparent that the assay can also be used to identify and/orisolate a receptor of a human eotaxin.

In one embodiment used to test for an inhibitor, a compositioncomprising cells capable of migration in response to human eotaxin areplaced in the first chamber. A composition comprising an isolated and/orrecombinant human eotaxin, portion thereof or variant, and optionally,one or more other ligand(s) or promoter(s) also capable of inducingchemotaxis of the cells in the first chamber (having chemoattractantfunction), is placed in the second chamber. Either before the cells areplaced in the first chamber, or simultaneously with the cells, acomposition comprising the agent to be tested is placed, preferably, inthe first chamber. Agents which can interfere with the ability of thehuman eotaxin, portion or variant to bind eotaxin receptor and inhibitthe induction of chemotaxis, of the cells present in the first chamberare inhibitors of stimulatory function. A reduction in the extent ofcell migration induced in the presence of the test agent is indicativeof inhibitory activity. Separate binding studies (see above) could beperformed to determine whether inhibition is a result of binding of thetest agent to receptor or to the human eotaxin, portion or variant, oroccurs via a different mechanism.

For instance, antibodies can be assessed for activity as inhibitors orpromoters in a chemotaxis assay as described herein. For example, toassess inhibition, chemotaxis of eosinophils in response to a humaneotaxin (in the lower chamber; see e.g., FIG. 3) can be monitored. Forexample, an antibody (e.g., an antibody raised against a synthetic humaneotaxin) can be placed in the lower chamber and the effect on chemotaxisin response to the human eotaxin can be assessed. As a control,chemotaxis in response to a human eotaxin in a no antibody control or inthe presence of a control antibody (e.g., preimmune serum) (placed inthe lower chamber with chemokine) is measured.

In vivo assays which monitor leukocyte infiltration of a tissue, inresponse to injection of an agent such as a human eotaxin or promoter ofhuman eotaxin, are described below (Models of Inflammation; Example 10).These models measure the ability of cells to respond to a ligand orpromoter by emigration and chemotaxis to a site of inflammation. Theeffect of an inhibitor on leukocyte infiltration induced by a ligand orpromoter can also be assessed in this type of assay.

In addition to the methods described, the effects of a human eotaxin,inhibitor or promoter of human eotaxin on the stimulatory functionmediated through receptor binding can be assessed by monitoring cellularresponses induced by active receptor, using eosinophils or suitable hostcells containing receptor. Similarly, these assays can be used todetermine the identity and function of a receptor. For instance,exocytosis (e.g., degranulation of eosinophils leading to release ofeosinophil cationic protein and/or one or more enzymes, or other granulecomponents; release of histamine from basophils), inflammatory mediatorrelease (such as release of bioactive lipids such as leukotrienes (e.g.,leukotriene C₄)), and respiratory burst (Rot, A. et al., J. Exp. Med.,176: 1489-1495 (1992)), can be monitored by methods known in the art orother suitable methods. See e.g., Bischoff, S. C. et al., Eur. J.Immunol. 23: 761-767 (1993) and Baggiolini, M. and C. A. Dahinden,Immunology Today, 15:127-133 (1994) and references cited therein).

In one embodiment, a human eotaxin, inhibitor or promoter is identifiedby monitoring the release of an enzyme upon degranulation or exocytosisby a cell capable of this function. Suitable cells capable of exocytosisor degranulation in response to receptor binding, including leukocytes(e.g., eosinophils, basophils) or other cells expressing an eotaxinreceptor, such as those containing a nucleic acid which encodes areceptor protein, are maintained in a suitable medium under suitableconditions (e.g., whereby receptor is expressed and wherebydegranulation can be induced). The cells are contacted with an agent tobe tested, and enzyme release is assessed. The release of an enzyme intothe medium can be detected or measured using a suitable assay, such asin an immunological assay, or biochemical assay for enzyme activity.

The medium can be assayed directly, by introducing components of theassay (e.g., substrate, co-factors, antibody) into the medium (e.g.,before, simultaneous with or after the cells and compound are combined).Alternatively, the assay can be performed on medium which has beenseparated from the cells or further fractionated prior to assay.

For example, convenient assays are available for enzymes such asβ-glucuronidase and eosinophil peroxidase (White, S. R. et al., Akinetic assay for eosinophil peroxidase activity in eosinophils andeosinophil conditioned media, J. Immunol. Methods, 144(2): 257-63(1991)).

Stimulation of degranulation by an agent can be indicative that theagent is a promoter of human eotaxin. Inhibition of degranulation isindicative of an inhibitor. In this embodiment, the cells are combinedwith a ligand or promoter, and a compound to be tested is added before,after or simultaneous therewith.

Models of Inflammation

A variety of in vivo models of inflammation are available, which can beused to assess the effects of human eotaxin (or of inhibitors orpromoters thereof) in vivo as therapeutic and/or prophylactic agents.

For example, primate models with eosinophilic infiltration to the lung,are available for in vivo testing (see e.g., Wegner, C. D. et al.,Science, 247: 456 (1990)). In one embodiment, an antibody (e.g., amonoclonal antibody) reactive with human eotaxin, and which cross-reactswith primate eotaxin, is administered to the animal. In anotherembodiment, an active human eotaxin, portion or variant is administeredto the animal to induce inflammation before, simultaneously with orafter administration of an antibody reactive with the human eotaxinpolypeptide. A number of parameters can be measured to assess in vivoefficacy including, but not limited to, the number of eosinophils in asample (e.g., in bronchoalveolar lavage fluid), respiratory compliance,and respiratory rate. A decrease in symptoms of airway hypersensitivitycan also be indicative of therapeutic benefit.

In addition, a sheep model for asthma, a guinea pig model for passivecutaneous anaphylaxis, or other suitable models can be used to assess anagent (e.g., an antibody) in vivo (see e.g., Weg, V. B. et al., J. Exp.Med., 177: 561 (1993); Abraham, W. M. et al., J. Clin. Invest., 93: 776(1994)).

In addition, leukocyte infiltration upon intradermal injection of anagent into a suitable animal, such as a primate (e.g., rhesus monkey),rabbit, rat, mouse or guinea pig, can be monitored (Example 10; seealso, Van Damme J. et al., J. Exp. Med., 176: 59-65 (1992); Zachariae,C. O. C. et al., J. Exp. Med. 171: 2177-2182 (1990); Jose, P. J. et al.,J. Exp. Med. 179: 881-887 (1994)). In one embodiment, skin biopsies areassessed histologically for infiltration of leukocytes (e.g.,eosinophils, granulocytes). In another embodiment, labeled cells (e.g.,stably transfected cells expressing an eotaxin receptor, labeled with¹¹¹In for example) capable of chemotaxis and extravasation areadministered to the animal. Infiltration of cells in response toinjection of a test sample (e.g., an agent to be tested in a suitablebuffer or physiological carrier) is indicative of the presence of ahuman eotaxin or promoter, such as an agonist, in the sample. Theseassays can also be modified to identify inhibitors of chemotaxis andleukocyte extravasation. For example, an inhibitor can be administered,either before, simultaneously with or after a human eotaxin polypeptideor agonist is administered to the test animal. A decrease in the extentof infiltration in the presence of inhibitor as compared with the extentof infiltration in the absence of inhibitor is indicative of inhibition.

Diagnostic Applications

The present invention has a variety of diagnostic applications. Theseapplications include, but are not necessarily limited to theapplications discussed herein.

Mutation(s) in genes encoding a human eotaxin can cause defects in atleast one function of the encoded polypeptide, thereby reducing orenhancing eotaxin function. For instance, mutations which produce avariant of eotaxin or alter the level of expression, can reduce orenhance eotaxin function, thereby reducing or enhancing, theinflammatory processes mediated by eotaxin.

For example, the nucleic acids of the present invention provide reagents(e.g., probes, PCR primers) which can be used to identify, screen for,characterize and/or isolate a defective human eotaxin gene, whichencodes a polypeptide having reduced or enhanced activity relative to astandard (e.g., wild type). Standard methods of screening for adefective gene can be employed, for instance. A defective gene can beisolated and expressed in a suitable host cell for further assessment ofthe gene and/or encoded protein.

In one embodiment, the methods of detecting or measuring eotaxin can beused diagnostically to characterize the activity of eotaxin produced byan individual. In these assays, reduced or enhanced eotaxin function canbe assessed. For example, antibodies raised against a protein of thepresent invention (see above) can be used in the diagnosis of diseasesor conditions in which increased or decreased leukocyte (especiallyeosinophil) activation or stimulation are observed, as indicated by, forexample hypereosinophilia (e.g., in hypereosinophilic syndrome) orhypoeosinophilia.

In one embodiment, antibodies of the present invention can be used todetect or measure decreased or increased expression of eotaxin invarious diseases or conditions in which inflammatory processes ofleukocytes are altered (e.g., increased or decreased relative to asuitable control, such as the level of expression in a normalindividual). The antibodies of the present invention can be used inprocedures in which human eotaxin is detected in a sample (e.g., tissuesor body fluids from an individual such as blood, serum, bronchoalveolarlavage fluid, saliva, bowel fluid). For example, a sample (e.g., tissueand/or fluid) can be obtained from an individual and a suitableimmunological method can be used to assess the level of expression.Suitable methods include methods such as enzyme-linked immunosorbentassays (ELISA), including chemiluminescence assays, radioimmunoassay,and immunohistology. For instance, the presence of an increased level ofeotaxin reactivity in a sample obtained from an individual can beindicative of inflammation and/or leukocyte (e.g., eosinophil)infiltration and/or accumulation associated with an inflammatory diseaseor condition, such as asthma, allergic rhinitis, or an infection, suchas a parasitic infection. The colocalization of elevated levels ofeotaxin and leukocytes such as eosinophils in inflamed tissue (nasalpolyp) compared with controls, as assessed immunohistologically withanti-eotaxin monoclonal antibodies, establishes an association betweeneotaxin and inflammation (Example 9).

Transgenic Animals

Transgenic animals, in which the genome of the animal host is alteredusing recombinant DNA techniques, can be constructed. In one embodiment,the alteration is not heritable (e.g., somatic cells, such as progenitorcells in bone marrow, are altered). In another embodiment, thealteration is heritable (the germ line is altered). Transgenic animalscan be constructed using standard techniques or other suitable methods(see e.g., Cooke. M. P. et al., Cell, 65: 281-291 (1991) regardingalteration of T lymphocytes; Hanahan, D., Science, 246: 1265-1275,(1989)).

In one aspect, an endogenous mammalian eotaxin gene can be inactivatedor disabled, in whole or in part, in a suitable animal host (e.g., bygene disruption techniques) to produce a transgenic animal. Nucleicacids of the present invention can be used to assess successfulconstruction of a host containing an inactivated or disabled eotaxingene (e.g., by Southern hybridization). In addition, successfulconstruction of a host containing an inactivated or disabled eotaxingene can be assessed by suitable assays which monitor the function ofthe encoded protein.

In another embodiment, a nucleic acid encoding a human eotaxin, portionthereof or variant, is introduced into a suitable host to produce atransgenic animal. In a preferred embodiment, endogenous eotaxin genespresent in the transgenic animals are inactivated (e.g., simultaneouslywith introduction of the nucleic acid by homologous recombination, whichdisrupts and replaces the endogenous gene). For example, a transgenicanimal (e.g., a mouse, guinea pig, sheep) capable of expressing anucleic acid encoding a human eotaxin in leukocytes (such aseosinophils, lymphocytes (e.g., T lymphocytes)) can be produced, andprovides a convenient animal model for assessing the function of theintroduced gene and encoded protein (Jose et al., Biochem. Biophys. Res.Commun., 205(1): 788-794 (1994); Rothenberg et al., J. Exp. Med., 181:1211-1216 (1995)). In addition, an agent can be administered to thetransgenic animal, and the effect of the agent on an inflammatoryprocess mediated by eotaxin can be monitored in a suitable assay (seee.g., Weg, V. B. et al., J. Exp. Med., 177: 561 (1993); Abraham, W. M.et al., J. Clin. Invest., 93: 776 (1994)). In this manner, agents whichare inhibitors or promoters of eotaxin can be identified or assessed forin vivo effect.

Methods of Therapy

Modulation of human eotaxin function according to the present invention,through the inhibition or promotion of at least one functioncharacteristic of human eotaxin, provides an effective and selective wayof inhibiting or promoting leukocyte-mediated inflammatory action. Oneor more inhibitors and/or promoters of human eotaxin function, such asthose identified as described herein, can be used to modulate leukocytefunction for therapeutic and/or prophylactic purposes.

As major eosinophil chemokine, eotaxin provides a target for selectivelyinterfering with or promoting leukocyte, especially eosinophil functionin a primate, such as a human. Accumulation of eosinophils is observedin certain inflammatory infiltrates. As shown herein, a synthetic humaneotaxin can recruit eosinophils in vivo (Example 10). The presentinvention provides a method of inhibiting or promoting an inflammatoryresponse in an individual (e.g., a primate, such as a human), comprisingadministering an agent which inhibits or promotes eotaxin function to anindividual in need of therapy or prophylaxis. Thus, agents which inhibitor promote human eotaxin function, inhibitors and promoters identifiedaccording to the present method, including human eotaxins (e.g., anisolated and/or recombinant human eotaxin having the same amino acidsequence as a naturally occurring human eotaxin) are particularly usefulfor modulating eosinophil function for therapeutic and/or prophylacticpurposes.

In one embodiment, an agent which inhibits one or more functions ofhuman eotaxin is administered to inhibit (e.g., reduce or prevent)inflammation. As a result, one or more inflammatory processes, such asleukocyte emigration, chemotaxis, exocytosis (e.g., of enzymes,histamine) or inflammatory mediator release, is inhibited. For example,eosinophilic infiltration to inflammatory sites (e.g., in asthma) can beinhibited according to the present method.

In another embodiment, an agent which promotes one or more functions ofeotaxin is administered to stimulate (e.g., induce or enhance) aninflammatory response, such as leukocyte (especially eosinophil)emigration, chemotaxis, exocytosis (e.g., of enzymes, histamine) orinflammatory mediator release, resulting in the beneficial stimulationof inflammatory processes. For example, eosinophils can be recruited tocombat parasitic infections.

The term “individual” is defined herein to include animals such asmammals, including, but not limited to, humans, primates, cows, sheep,goats, horses, dogs, cats, guinea pigs, rats or other bovine, ovine,equine, canine, feline, rodent or murine species.

Diseases and conditions associated with inflammation and infection canbe treated using the method. In a preferred embodiment, the disease orcondition is one in which the actions of eosinophils and/or otherleukocyte types are to be inhibited or promoted, in order to modulatethe inflammatory response.

Diseases or conditions of humans especially, as well as non-humanprimates or other species which can be treated with inhibitors of humaneotaxin function, include, but are not limited to:

-   -   inflammatory or allergic diseases and conditions, including        respiratory allergic diseases such as asthma, allergic rhinitis,        hypersensitivity lung diseases, hypersensitivity pneumonitis,        eosinophilic pneumonias (e.g., Loeffler's syndrome, chronic        eosinophilic pneumonia), interstitial lung diseases (ILD) (e.g.,        idiopathic pulmonary fibrosis, or ILD associated with rheumatoid        arthritis, systemic lupus erythematosus, ankylosing spondylitis,        systemic sclerosis, Sjogren's syndrome, polymyositis or        dermatomyositis); systemic anaphylaxis or hypersensitivity        responses, drug allergies (e.g., to penicillin, cephalosporins),        insect sting allergies; inflammatory bowel diseases, such as        Crohn's disease and ulcerative colitis; spondyloarthropathies;        scleroderma; psoriasis and inflammatory dermatoses such as        dermatitis, eczema, atopic dermatitis, allergic contact        dermatitis, urticaria; vasculitis (e.g., necrotizing, cutaneous,        and hypersensitivity vasculitis);    -   eosinophilic myositis, eosinophilic fasciitis;    -   autoimmune diseases, such as rheumatoid arthritis, psoriatic        arthritis, multiple sclerosis, systemic lupus erythematosus,        myasthenia gravis, juvenile onset diabetes, glomerulonephritis,        autoimmune thyroiditis, Behcet's disease;    -   graft rejection (e.g., in transplantation), including allograft        rejection or graft-versus-host disease;    -   cancers with leukocyte infiltration of the skin or organs;    -   other diseases or conditions in which undesirable inflammatory        responses are to be inhibited can be treated, including, but not        limited to, reperfusion injury, atherosclerosis, certain        hematologic malignancies, cytokine-induced toxicity (e.g.,        septic shock, endotoxic shock), polymyositis, dermatomyositis.

Diseases or conditions of humans, non-human primates, or other specieswhich can be treated with promoters of eotaxin function, include, butare not limited to:

-   -   immunosuppression, such as that in individuals with        immunodeficiency syndromes such as AIDS, individuals undergoing        radiation therapy, chemotherapy, therapy for autoimmune disease        or other drug therapy (e.g., corticosteroid therapy), which        causes immunosuppression;    -   immunosuppression due to congenital (or other) deficiency in        eotaxin or other causes;    -   infectious diseases, such as parasitic diseases, including, but        not limited to helminth infections, such as nematodes (round        worms); (Trichuriasis, Enterobiasis, Ascariasis, Hookworm,        Strongyloidiasis, Trichinosis, filariasis); trematodes (fluxes)        (Schistosomiasis, Clonorchiasis), cestodes (tape worms)        (Echinococcosis, Taeniasis saginata, Cysticercosis); visceral        worms, visceral larva migrans (e.g., Toxocara), eosinophilic        gastroenteritis (e.g., Anisaki spp., Phocanema spp.), cutaneous        larva migrans (Ancylostoma braziliense, Ancylostoma caninum).

Eosinophils as the Target Cell in Certain Inflammatory Reactions,Particularly Asthma

Eosinophils are produced in the bone marrow and circulate to thetissues, predominantly to mucosal tissues, such as the lungs,gastrointestinal tract, and genitourinary tract. Eosinophils typicallyconstitute 1-3% of leukocytes in the blood. However, in people sufferingfrom allergic diseases and helminthic parasitic infections, increasedeosinophil accumulation occurs in the tissues or the blood. Eosinophilsaccumulation can be both beneficial and detrimental to the host.

For example, eosinophils possess numerous granules, containing cationicproteins. Degranulation of eosinophils, triggered, for example, by theengagement of IgG, IgA, or IgE receptors, or by stimulation byinflammatory mediators such as platelet-activating factor (PAF),leukotrienes, or chemokines, leads to release of the components in thegranule. Products from eosinophils also cause damage to host cells. Themost damaging are the cationic proteins, which are detectable inelevated concentrations in patients with asthma. Eosinophils alsogenerate a number of inflammatory mediators, including Leukotriene C4,and platelet-activating factor (PAF). These mediators contract airwaysmooth muscle, promote the secretion of mucus, alter vascularpermeability, and elicit further eosinophil and neutrophil infiltration.

Eosinophils are involved in the initiation and maintenance ofallergic/asthma diathesis. Thus, in a preferred embodiment, the methodcan be used to treat asthma or hypersensitivity (allergic) states,particularly those involving mucosal tissues, as well as in othereosinophil-associated diseases. In a particularly preferred embodiment,an agent (e.g., an antibody) which inhibits one or more functions ofhuman eotaxin is administered to an individual with asthma.

Eosinophils are clearly important in the host defense against anddestruction of, large, nonphagocytable organisms, such as multicellularhelminthic parasites. Eosinophils are also important effector cells inimmune reactions against other pathogens that induce high levels of IgEantibodies. Accordingly, the method can be used to treat infectiousdiseases, such as parasitic diseases, to stimulate or promoteinflammatory defenses, or to suppress inflammatory responses which aredestructive to the host.

Eosinophils and Asthma Pathogenesis

Asthma is characterized by the obstruction of the airways or bronchi,and results from a bronchial hyperresponsiveness and rapid constrictionin response to a wide range of pharmacological mediators. Chronicinflammation of the bronchial mucosal lining is believed to play afundamental role in the development of asthma.

Intense infiltration of the bronchial mucosa with eosinophils,macrophages and lymphocytes is observed in asthma and otherhypersensitivities. Often the selective migration of eosinophils toinflamed airways can be striking, and appears to result from theselective binding of eosinophils to endothelium and extraction from theblood. Eosinophils in particular are implicated as the causative agentsof bronchial mucosal injury. Studies of asthmatic patients suggest thatblood eosinophil counts correlate with the degree of bronchialhyperresponsiveness. In addition, bronchial biopsies and bronchoalveolarlavage fluid from asthmatics show a clear relationship between thedegree of eosinophilia and clinical severity. Thus, there is a strongconnection between the presence of eosinophils and adverse immunereactions, particularly in asthma.

A novel human chemokine that selectively stimulates activation,chemotaxis, and/or extravasation of leukocytes such as eosinophils,provides an excellent target for interfering with eosinophilrecruitment. For example, administration of an inhibitor of at least onefunction of human eotaxin, such as by inhibiting binding to a receptorwhich binds thereto, can provide an effective and selective way oftreating asthma. By reducing or preventing recruitment (extravasation,infiltration) of leukocytes, particularly eosinophils, to inflamed lungand airway tissues, and/or reducing leukocyte (especially eosinophil)function in those tissues, the destructive inflammatory processes ofasthma can be inhibited, and the symptoms alleviated.

There is evidence that the blockage of eosinophil recruitment to thelung can alleviate the symptoms of asthma. Administration of amonoclonal antibody reactive with α4 integrin was reported to inhibitthe accumulation of eosinophils into the lung and airways, and blockedthe airway hyperresponsiveness to antigen challenge in sheep. In aprimate model of asthma, a monoclonal antibody to ICAM-1 is reported toattenuate airway eosinophilia and hyperresponsiveness. In addition, in aguinea pig model for passive cutaneous anaphylaxis, in vitropretreatment of eosinophils with the anti-α4 monoclonal was reported tosuppress eosinophil accumulation. (see Wegner, C. D. et al., Science,247: 456 (1990); Weg, V. B. et al., J. Exp. Med., 177: 561 (1993); andAbraham, W. M. et al., J. Clin. Invest., 93: 776 (1994) regarding thesemodels).

Desensitization of Eosinophils

RANTES, which is a chemoattractant of monocytes and T cells, is also achemoattractant for eosinophils. RANTES binds specifically and with highaffinity to CKR-3 receptor protein (U.S. Ser. No. 08/375,199, filed Jan.19, 1995). As shown herein (FIGS. 6A-6E), an isolated, purified humaneotaxin of the present invention can desensitize eosinophils to RANTESor to human eotaxin. Moreover, the desensitization appears to bespecific for the CKR-3 receptor, as eotaxin did not desensitizeeosinophils to anaphylatoxin C5a, which binds to eosinophils through adistinct receptor. Thus, the present invention provides a method ofdesensitizing eosinophils to chemokines which activate and/or stimulateeosinophil function. Receptor-specific desensitization in whicheosinophils are rendered unresponsive or less responsive to one or moreligands of a selected chemokine receptor present on eosinophils, ispossible according to the present invention. Eosinophils in blood ortissues, can be desensitized to RANTES and/or human eotaxin present ine.g., lungs or airways, whereby eosinophil activation and/or stimulationis inhibited (reduced or prevented). The method of desensitizingeosinophils is useful therapeutically and/or prophylactically in thetreatment of inflammatory or allergic diseases and conditions,particularly allergic hypersensitivity diseases (e.g., allergicrhinitis, asthma).

The specificity of desensitization permits specific inhibition ofeosinophil function (e.g., activation and/or stimulation) triggered byengagement of the specific C—C chemokine receptor. In a preferredembodiment, the agent administered desensitizes eosinophils, but hasreduced eosinophil activation function, and preferably reduced inductionof exocytosis and/or inflammatory mediator release (e.g., as comparedwith naturally occurring human eotaxin or a protein having the sameamino acid sequence as naturally occurring human eotaxin).

According to the method, isolated and/or recombinant human eotaxin, afunctional portion thereof or functional variant of human eotaxin isadministered to an individual (e.g., a human) in a therapeuticallyeffective amount (e.g., an amount sufficient to desensitize eosinophilsin the blood and/or tissues, whereby inflammation due to eosinophilactivation and/or stimulation is inhibited (reduced or prevented)). Theisolated and/or recombinant human eotaxin, functional portion thereof orvariant of human eotaxin can be administered by a suitable route (seebelow).

Eosinophils and Cancer

Cellular infiltrates containing predominantly eosinophils andmacrophages have been observed in the area surrounding a plasmacytoma ina mouse model (Tepper, R. I. et al., Cell, 57: 503-512 (1989)). Thepresent invention provides a method of anti-tumor therapy, in which anisolated and/or recombinant human eotaxin, a functional portion thereofor functional variant of human eotaxin is used in tumor therapy tospecifically recruit eosinophils to the site of a tumor (e.g., a solidtumor such as a melanoma, carcinoma, sarcoma or leukemia (e.g., lymphomawith infiltration)). In one embodiment, colon cancer can be treatedaccording to the claimed method. In particular, isolated and/orrecombinant human eotaxin, a functional portion thereof or variant ofhuman eotaxin is administered to an individual (e.g., a human) in atherapeutically effective amount (e.g., an amount sufficient to recruiteosinophils to the site, whereby tumor growth is inhibited and/orinduced tumor regression occurs). The isolated and/or recombinant humaneotaxin, a functional portion thereof or variant of human eotaxin isadministered by a suitable route, and preferably by injection (e.g.,intratumoral injection or injection), to achieve a local concentrationsufficient for an anti-tumor effect.

Modes of Administration

According to the method, one or more agents can be administered to thehost by an appropriate route, either alone or in combination withanother drug. An effective amount of an agent (e.g., a peptide whichinhibits eotaxin binding, an antibody or antibody fragment) isadministered. An effective amount is an amount sufficient to achieve thedesired therapeutic or prophylactic effect, under the conditions ofadministration, such as an amount sufficient for inhibition or promotionof chemokine (e.g., human eotaxin) function, and thereby, inhibition orpromotion, respectively, of an inflammatory response.

A variety of routes of administration are possible including, but notnecessarily limited to oral, dietary, topical, parenteral (e.g.,intravenous, intraarterial, intramuscular, subcutaneous injection), andinhalation (e.g., intrabronchial, intranasal or oral inhalation,intranasal drops) routes of administration, depending on the disease orcondition to be treated. For respiratory allergic diseases such asasthma, inhalation is a preferred mode of administration.

Formulation of an agent to be administered will vary according to theroute of administration selected (e.g., solution, emulsion, capsule). Anappropriate composition comprising the agent to be administered can beprepared in a physiologically acceptable vehicle or carrier. Forsolutions or emulsions, suitable carriers include, for example, aqueousor alcoholic/aqueous solutions, emulsions or suspensions, includingsaline and buffered media. Parenteral vehicles can include sodiumchloride solution, Ringer's dextrose, dextrose and sodium chloride,lactated Ringer's or fixed oils. Intravenous vehicles can includevarious additives, preservatives, or fluid, nutrient or electrolytereplenishers (See, generally, Remington's Pharmaceutical Science, 16thEdition, Mack, Ed. 1980). For inhalation, the agent is solubilized andloaded into a suitable dispenser for administration (e.g., an atomizer,nebulizer or pressurized aerosol dispenser).

Furthermore, where the agent is a protein or peptide (such as a humaneotaxin), the agent can be administered via in vivo expression of therecombinant protein. In vivo expression can be accomplished via somaticcell expression according to suitable methods (see, e.g., U.S. Pat. No.5,399,346). In this embodiment, the DNA encoding the protein can beincorporated into a retroviral, adenoviral or other vector (preferably,a replication deficient infectious vector) for delivery, or can beintroduced into a transfected or transformed host cell capable ofexpressing the protein for delivery. In the latter embodiment, the cellscan be implanted (alone or in a barrier device) or injected in an amounteffective to express the protein in a therapeutically effective amount.

EXEMPLIFICATION

The present invention will now be illustrated by the following Examples,which are not intended to be limiting in any way.

Example 1 Isolation of a Human Genomic Clone

The reported guinea pig eotaxin amino acid sequence (Jose, P. J. et al.,J. Exp. Med., 179: 881-887 (1994)) was used to design degenerate primersfor polymerase chain reaction (PCR) amplification of sequences from bothhuman genomic DNA and human asthmatic lung tissue. Clones were isolatedand analyzed by DNA sequencing. Of ˜25 clones sequenced, some clonesshared sequence similarity to known chemokines, but none appeared to besufficiently related to guinea pig eotaxin to be the human homolog.

Next, a fragment isolated from a mouse cDNA clone designated Clone 28,was used as a probe. Clone 28 (provided by Jose-Carlos Gutierrez-Ramos,Center for Blood Research, Boston, Mass.), was obtained by reversetranscription and polymerase chain reaction using an RT-PCR kit(Perkin-Elmer) with RNA isolated from inflamed, eosinophilic lung tissueobtained from BALB/c mice sensitized to ovalbumin (OVA) in anexperimentally induced inflammation model. The degenerate primers usedin RT-PCR for the isolation of Clone 28 were designed based on theguinea pig eotaxin amino acid sequence. Restriction digestion of Clone28 with EcoRI released a ˜200 bp Eco RI fragment from the pCR™II vectorof the clone. The fragment was separated from vector by agarose gelelectrophoresis, and purified by electroelution. Approximately 200 ng ofmaterial was labeled with ³²P using a Random Primed DNA Labeling Kit(Boehringer Mannheim) according to the manufacturer's recommendedprotocol.

Library Screening

A human genomic library in vector EMBL3 SP6/T7 was purchased fromClontech (Catalog No. HL 1111). For each of thirty 150 mm plates,approximately 25,000 plaque forming units were mixed with 600 μls of anovernight bacterial culture of E. coli strain K802 (provided with thelibrary) in NZCYM top agarose, and plated on a 150 mm petri dishcontaining NZCYM agar (NZYCM broth, agar and agarose were purchased fromGibco/BRL). After incubation at 37° C. for 7 hours, the plates wereoverlaid with BA-85 nitrocellulose membranes (Schleicher and Schuell,Keene, N.H.) for 10 minutes to allow transfer of phage to membrane. Themembranes were then soaked for 5 minutes in Denaturing Solution (1.5 Msodium chloride, 0.5 N sodium hydroxide) followed by neutralization in1.5 M sodium chloride, 0.5 M Tris, pH 8.0. The filters were allowed toair dry for 15 minutes and were then baked for two hours at 80° C. undervacuum. Hybridization with the probe (see above) was carried outovernight at 65° C. in 6×SSC (1×SSC is 0.15 M sodium chloride, 0.015 Msodium citrate) containing 5×Denhardt's solution (1×Denhardt's solutionis 0.02% bovine serum albumin, 0.02% ficoll, 0.02% polyvinylpyrolidone),10% w/v dextran sulfate, 2% SDS, and sheared salmon sperm DNA (100μg/ml). The membranes were rinsed twice in 2×SSC, 0.5% SDS at 65° C. (5min each), followed by two washes (15 min each) in 0.2×SSC, 0.5% SDS at55° C.

Eleven positive clones were detected using these conditions of moderatestringency. Plaques were picked from the primary library screen, andwere purified by diluting the primary phage several fold and reprobingwith the original probe until a single well-isolated positive plaque wasobtained. One phage clone, designated Clone 25 (also referred to as25H3), having an approximately 15-20 kb insert, was found to contain asequence sharing similarity to that reported for guinea pig eotaxin. Thecoding region for this human gene was contained within a ˜5.5 kb PstIfragment present in Clone 25. This PstI fragment was subcloned into thePstI site of Bluescript® II KS+ (Stratagene) to yield a constructdesignated 25PstI. Transformants of 25PstI in DH5α were obtained. Theinsert of 25PstI was subjected to sequence analysis using the Sequenase™7-deaza-dGTP DNA Sequencing Kit with Sequenase Version 2.0 T7 DNApolymerase (United States Biochemical (USB), Amersham Life Science). Thesequence determined for the human gene is presented in FIG. 1A-1B (SEQID NO:1).

Example 2 Isolation of a Human cDNA Clone

Using specific primers, a candidate human eotaxin cDNA clone wassubsequently amplified by RT-PCR (reverse transcription, polymerasechain reaction) from RNA isolated from spleen, thymus, eosinophils, andmonocytes in separate amplification reactions. Spleen and thymus mRNAwere purchased from Clontech (spleen RNA, Catalog No. 6542-1; thymusRNA, Catalog No. 6536-1). Eosinophils and monocytes were isolated asdescribed below in Example 4, and total RNA was isolated using TRIzol™Reagent (GIBCO/BRL) according to the manufacturer's protocol.

20-50 ng of mRNA or 5 μg of total RNA was reverse transcribed with oligodT. 2-5 μl of this cDNA was mixed with 200 μM dNTPs and 50-100 pmol ofprimer in a 50 μl volume for amplification with 5 units of Amplitaqpolymerase. Magnesium concentration was 2.5 mM. The primers used for PCRamplification were:

5′ primer (SEQ ID NO:7): Bam HI 5′-GGA TCC AAC ATG AAG GTC TCC G-3′3′ primer (SEQ ID NO:8): EcoRI 5′-GAA TTC TTA TGG CTT TGG AGT TGG AG-3′The cycle parameters for PCR were as follows:

95° C., 1 minute;

25 cycles of:

-   -   94° C., 30 seconds;    -   68° C., 10 seconds;    -   72° C., 10 seconds;    -   72° C., 6 minutes.

The amplification reaction yielded a single size of fragment (˜300 bp).The PCR product was gel purified, digested with BamHI and EcoRI, andinserted into the BamHI and EcoRI sites of plasmid Bluescript® II KS+(Stratagene) to yield a cDNA clone designated #25. cDNA clone #25 wasproduced by RT-PCR from spleen. Transformants of the #25 clone in DH5αwere obtained. The insert of cDNA clone #25 was subjected to sequenceanalysis using the Sequenase 7-deaza-dGTP DNA Sequencing Kit withSequenase Version 2.0 T7 DNA polymerase (United States Biochemical(USB), Amersham Life Science).

The sequence of the human cDNA determined from cDNA clone #25 ispresented in FIG. 2 (SEQ ID NO:3). The encoded protein contains thepaired, adjacent cysteine residues typical of C—C chemokines atpositions 32-33. Alignment of the amino acid sequence of the proteinencoded by cDNA clone #25 with other C—C chemokines indicates that theencoded protein also has a leader sequence for secretion. Based on thealignment with other C—C chemokines, the leader sequence corresponds toamino acids 1-23 of the predicted protein, and the mature protein beginswith amino acid 24 (Gly²⁴).

The amino acid sequence of the predicted mature polypeptide encoded byclone #25 (residues 24-97) was compared to that of other known C—Cchemokines (without leader peptides) (including human MCP-1, humanMCP-2, guinea pig eotaxin, human MCP-3, human MIP-1β, human MIP-1α, andhuman RANTES) using the Lasergene Biocomputing Software from DNASTAR(Madison, Wis.). In addition, the complete open reading frame of thehuman cDNA (including the nucleotides encoding the leader peptide) wascompared to those of other known C—C chemokines. The results of thisanalysis indicated that the predicted mature human protein encoded bycDNA #25 shares 64%, 62.7%, 62.7% and 58.1% amino acid sequencesimilarity with human MCP-1, human MCP-2, human MCP-3, and guinea pigeotaxin, respectively. Other sequences were less related. Given thesequence similarity with MCP-1, a monocyte and T cell chemoattractant,the biological activity of the protein encoded by clone #25 was assessedin order to establish its relationship to the other C—C chemokines. Atthe nucleotide level, the human cDNA #25 sequence was found to share72.1% and 74.6% nucleic acid sequence similarity with human MCP-1 andguinea pig eotaxin, respectively, and to share 75.6% sequence similaritywith the sequence of the mouse gene used as a probe.

As described in more detail below, the predicted mature protein encodedby genomic clone 25 (Example 1) and cDNA clone #25 has been produced. Asis further described herein, the protein is a potent and specificchemoattractant for eosinophils, and therefore is referred to herein ashuman eotaxin. This novel chemotactic cytokine can be classified as amember of the C—C branch of chemotactic cytokines.

Example 3 Chemical Synthesis and Purification of Human Eotaxin ChemicalSynthesis

A human eotaxin polypeptide (amino acids 24-97) was synthesized by usingsolid-phase methods (Merrifield, R. B., J. Am. Chem. Soc. 85: 2149-2154(1963)) that were optimized and adapted to a fully automated peptidesynthesizer (Applied Systems 430A) and described in detail elsewhere(Clark-Lewis, I. et al., Science 231: 134-139 (1986); Clark-Lewis, I.and S. Kent, (1989), In: The Use of HPLC in Receptor Biochemistry,Kerlavage, A. R., Ed., (Alan R. Liss: New York) pp. 43-75; and Kent, S.B. H., Annu. Rev. Biochem. 57: 957-989 (1988)). The synthesis wasstarted with the protected C-terminal amino acid linked to across-linked polystyrene resin via a 4-(carboxamidomethyl)benzyl esterlinkage (pam resin) (0.4 mmol of 0.8 mmol/g of aminoacyl resin).N^(α)-t-Boc amino acids with appropriate side chain protecting groupswere added in a step wise fashion until the entire protected polypeptidechain was formed. Side chain protection was as follows: benzyl (Asp,Glu, Ser, Thr); 4-methylbenzyl (Cys); toluenesulfenyl (Arg);2-chlorobenzyloxycarbonyl (Lys); 2-bromobenzyloxycarbonyl (Tyr); formyl(Trp); dinitrophenyl (His); and none (Ala, Asn, Gly, Gln, Ile, Leu, Met,Phe, Pro, Val). Samples were automatically taken after each step toretrospectively monitor the amino acid coupling yields usingninhydrin-based reaction (Sarin, V. K. et al., Anal. Biochem. 117:147-157 (1981)).

The resin was dried and cleaved by using the “low-high” hydrogenfluoride method as described (Tam, J. P. et al., J. Am. Chem. Soc. 105:6442-6455 (1983)), except for the following modifications. After the 25%hydrogen fluoride step, the partially protected peptide resin wasfiltered from the reaction mixture by using an all-Teflon filtrationapparatus fitted with a Zitex filter and washed with dichloromethane anddried before the high 90% hydrogen fluoride step. The ethyl acetateprecipitation of the material released from the resin was dissolved in50 ml of 6M guanidine hydrochloride, 0.1 M Tris-acetate, pH 8.5, and 20%2-mercaptoethanol and stirred at 37° C. for 2 hours and then acidifiedwith 2 ml of acetic acid. This mixture was termed the crude peptideproduct.

HPLC Purification and Folding

Three different C-18 silica columns were used in the purification andanalysis of the human protein, including (1) a preparative column(22.4×250 mm column with a 22.4×100 mm guard column) packed with 12-μm,300-Å pore size packing (Dynamax, Rainin Instrument Co., Woburn, Mass.);(2) a semipreparative (10×250 mm) Vydac C-18 column, with 5-mm particle,300-Å pore size packing (Separations Group, Hesperia, Calif.); and (3)an analytical 4.6×250 mm column (Vydac) containing the same packing. Thecrude peptide product was loaded onto the preparative column and theretained material eluted with a 0-60% water-acetonitrile gradient in0.1% trifluoroacetic acid over 4 hours at a flow rate of 15 ml perminute. A sample (25 μl) of fractions containing 225-nm UV-absorbingmaterial was rerun on the analytical column, and by comparison with theprofile of the crude material, fractions containing the major peak werepooled and lyophilized. This material was reconstituted in 1 M guanidinehydrochloride and Tris-acetate, pH 8.5, at a concentration of 0.2 mg/mland stirred vigorously overnight in an open beaker so that air was keptbubbling through the mixture by vortex action. This procedure has beenfound to promote formation of the disulfide bridges by oxidation of theappropriate half-cystines (Clark-Lewis, I. et al., Proc. Natl. Acad.Sci. USA, 85: 7897-7902 (1988); Woo, D. D. L. et al., Protein Eng. 3:29-37 (1989)). This material was acidified with 2 ml of acetic acid, andhalf was loaded onto the semipreparative column and the retainedmaterial eluted with the same gradient as before at a flow rate of 3ml/min. Samples of each fraction were run on the analytical column.Fractions containing only material with the retention time of the majorpeak in the folded material were pooled and lyophilized as purifiedeotaxin.

Example 4 Human Eotaxin is Chemotactic for Eosinophils, but notNeutrophils, T Cells or Monocytes

The chemotactic activity of the clone #25 polypeptide was assessed in asensitive chemotaxis assay that employs transendothelial migration(Carr, M. W. et al., “Monocyte chemoattractant protein 1 acts as aT-lymphocyte chemoattractant,” Proc. Natl. Acad. Sci. USA., 91: 3652-56(1994)). Human eosinophils, neutrophils, peripheral blood mononuclearcells (PBMC), and activated T cells were analyzed for their response todifferent concentrations of synthetic protein (Example 3) and otherchemokines.

Isolation and Preparation of Eosinophils, Neutrophils, Peripheral BloodMononuclear Cells, and Activated T Cells

100 ml of heparinized blood was diluted 1:1 with PBS. 20 ml aliquotswere layered over 65%, 75% Percoll step gradients. The gradients werecentrifuged at 1500 rpm, 25 min at room temp. The eosinophil/neutrophillayers were transferred to a new tube and erythrocytes lysed by additionof 20 mls 0.2% NaCl for 1 min followed by the addition of 30 mls 1.8%NaCl. Cells were washed twice with a buffer consisting of PBS, 0.5% BSA,0.5 mM EDTA. Cells were resuspended at 5×10⁷ cells/50 μl in cold buffer(PBS, 0.5% BSA, 0.5 mM EDTA) and 50 μl CD16 microbeads were added to thecells. The mixture was incubated at 4° C. for 25 min followed by theaddition of 900 μl cold buffer. The miniMACS™ separation unit (MiltenyiBiotec, Inc., Auburn Calif. 95603) was used to deplete CD16 positivecells (neutrophils). Cells were loaded onto the column in 200 μlaliquots. Flow-through cells were collected and assessed histologically.The eosinophil prep was >99% pure.

For the isolation of neutrophils or peripheral blood mononuclear cells(including monocytes and lymphocytes), a standard protocol was followed(Current Protocols in Immunology, 1992, Coligan, J. E., A. M. Kruisbeek,D. H. Margulies, E. M. Shevach, and W. Strober, Editors, (John Wiley &Sons, New York, N.Y.), Unit 7.23). Activated T cells were prepared usinganti-CD3 stimulation. Anti-CD3 mAb TR66 (obtained from Dr. A.Lanzavecchia, Basel Institute for Immunology, Basel) was coated onto 24well plates, using a solution of 5 μg/ml in PBS. After a 1 hourincubation at 37° C., the unbound antibody was removed, the plate waswashed four times with PBS, and 2×10⁶ PBMC were added per well in RPMI1640/10% fetal calf serum (FCS). Plates were incubated 3-4 days.

Monocytes were isolated using magnetic sorting with MACS using aprefilled and washed A2 column according to the Magnetic Sorting withMACS (10⁷-2×10⁸ positive cells); Protocol for 10⁷ cells provided by themanufacturer (Miltenyi Biotec, Inc., Sunnyvale, Calif.). Positive cellswere enriched for using a G23 needle.

Chemotaxis Assay

Chemokines were obtained from Peprotech, Inc. (Rocky Hill, N.J.), withthe exception of MCP-2 and synthetic eotaxin (predicted mature eotaxin(amino acids 24-97); Example 3) which were chemically synthesized.Chemotaxis experiments were performed using 3.0 micron Biocoat cellculture inserts (Collaborative Biomedical Products), in 24 well plates.Endothelial cells were grown to confluency on the inserts for two daysprior to chemotaxis experiments. The endothelial cells used were a cellline termed ECV 304 (European Collection of Animal Cell Cultures, PortonDown, Salisbury, U.K.), which expresses endothelial cell markers such asvon Willebrand factor, as well as ICAM-1 and VCAM-1. This endothelialcell line greatly facilitates these assays, since human umbilical veinendothelial cells can be variable in nature, can be used for onlyseveral passages, and grow much more slowly than ECV 304.

ECV 304 cells were grown as adherent monolayers in M199/10% FCS, andwere seeded onto the inserts (2×10⁵ cells per insert). Cells wereincubated at 37° C. in the M199/10% FCS medium.

The assay buffer consisted of equal parts M199 and RPMI 1640, with 0.5%FCS. The assay was conducted at 37° C. for 1.5 hours, migrated cellswere counted using either an inverted microscope, or a flow cytometer.Only cells which migrated completely into the bottom chamber werecounted.

FIGS. 4A-4D illustrate the chemotaxis of leukocyte subpopulations inresponse to 100 ng/ml of chemokine present in the bottom chamber (MCP-1,MCP-2, MCP-3, MIP-1α (MIP-1α), RANTES, interleukin-8 (IL-8), IP-10 (aC—X—C chemokine; Peprotech), MIP-1β, or human eotaxin (synthetic matureeotaxin (amino acids 24-97)). As indicated above, chemotaxis plates wereincubated at 37° C. for 90 minutes, and the cells which migrated to thebottom chamber were counted by microscopy (HPF=high power field). Theresults presented are a representative experiment of at least fourexperiments performed.

The clone #25 polypeptide was found to be a potent chemoattractant forhuman eosinophils, attracting eosinophils at levels approximately equalto or greater than that of the other eosinophilic chemoattractants, suchas RANTES and MCP-3 (FIG. 4D).

The dose response of human eosinophils to human eotaxin (syntheticmature) was also assessed in the transendothelial assay. Eosinophilswere purified as described above. 1, 10, 100, or 1000 ng/ml of chemokinewas present in the bottom chamber. Chemotaxis plates were incubated at37° C. for 90 minutes, and the cells which migrated from the upperchamber to the bottom chamber were counted using a flow cytometer. Theresults obtained using eosinophils obtained from three different donorsare shown in FIGS. 5A-5C. Donor to donor variation in the response ofeosinophils to eotaxin, RANTES and MCP-3 was observed.

Human eotaxin was not chemotactic for human neutrophils, monocytes oractivated T cells under the conditions used (FIGS. 4A-4C). Based uponthe ability of the clone #25 polypeptide to induce the chemotaxis ofeosinophils, and the lack of effect on other leukocytes cell typestested under the conditions of the assay, together with the sequencesimilarity of the encoded protein to guinea pig eotaxin, thepolypeptide(s) encoded by genomic clone 25 and cDNA clone #25 weredesignated human eotaxin.

Example 5 Effects of Human Eotaxin on Human Eosinophils A. Induction ofCalcium Flux

Human eotaxin was tested for its ability to induce calcium flux in humaneosinophils. Human eosinophils were isolated from peripheral blood byPercoll separation followed by CD16 magnetic bead treatment, asdescribed above.

Cells were labeled with the fluorochrome Fluo-3 (Molecular Probes)according to the following protocol. 50 μg of Fluo-3 was dissolved in 44μl of DMSO and diluted to 10 μM with modified Gay's buffer (MGB) (5 mMKCl, 147 mM NaCl, 0.22 mM KH₂PO₄, 1.1 mM Na₂HPO₄, 5.5 mM glucose, 0.3 mMMgSO₄.7H₂O, 1 mM MgCl₂, and 10 mM HEPES, pH 7.4). Cells were resuspendedin MGB to 10⁷ cells/ml, and incubated with an equal volume of 10 μMFluo-3 mix for 30 minutes at room temperature. Cells were then washedtwice with MGB and resuspended at 2×10⁶ cells/ml in MGB. The calciumflux to various chemokines was measured on the FACScan, by analyzingfluorescence intensity (linear scale) versus time.

FIG. 6A shows that 100 nM of human eotaxin was able to induce a strongcalcium flux in human eosinophils. The magnitude of the response wasgreater than that obtained with all other chemokines tested, includingRANTES, MCP-3, MCP-2, MIP-1α, and IL-8. This response was rapid andtransient.

B. Desensitization

Chemokine-mediated calcium flux desensitizes individual receptors tofurther stimulation with other specific ligands. This technique has beenused to establish the specificity of a chemokine for a given receptor,and the combinations of different ligands that bind to the one receptor(Uguccioni, M. et al., “Actions of the chemotactic cytokines MCP-1,MCP-2, MCP-3, RANTES, MIP-1 alpha and MIP-1 beta on human monocytes,”Eur. J. Immunol., 25: 64-68 (1995)). Desensitization was also assessedusing the calcium flux assay.

Human eotaxin polypeptide was able to desensitize eosinophils tosubsequent stimulation with eotaxin (FIG. 6E) or RANTES (FIG. 6A).However, prior stimulation of eosinophils with RANTES (FIG. 6B) orMIP-1α (FIG. 6C) was unable to completely desensitize the response tosubsequent stimulation with eotaxin. This may be because human eotaxinis binding to receptor(s) that cannot be bound/desensitized by any ofthe chemokines tested, or because human eotaxin induces such a strongresponse that weaker agonists are unable to desensitize the eotaxinreceptor on eosinophils. Nevertheless, RANTES was able to reduce themagnitude of the subsequent eotaxin response, indicating partialdesensitization.

Example 6 Competitive Binding Studies

The results of chemotaxis assays indicated that purified eosinophils andto a lesser extent, butyric acid differentiated HL-60 cells, respondedto human eotaxin, while other cell types tested did not. In order tofurther assess the relationship between human eotaxin and otherchemokines known to be active on these cells, competitive ligand bindingassays were performed.

HL-60 Cell Differentiation

HL-60 cells can differentiate down an eosinophilic pathway (Tagari, P.et al., Int. Arch. Allergy Immunol., 101: 227-233 (1993); Van Riper, G.et al., J. Immunol., 152: 4055-4061 (1994)). HL-60 cells (American TypeCulture Collection, Accession No. CCL 240) were resuspended in RPMI(without HEPES)+20% fetal calf serum (FCS) at 0.5×10⁶ cells/ml.n-Butyric acid (Sigma Chemical Co., St. Louis, Mo.; #B5887) was added toa final concentration of 0.4 mM from a stock solution of 1 M n-butyricacid. HL-60 cells were incubated at 37° C., 5% CO₂ for four days beforeharvesting.

Radioiodination of Human Eotaxin

Synthetic eotaxin (predicted mature protein consisting of amino acids24-97) was labeled with ¹²⁵I using Bolton-Hunter reagent according tothe manufacturer's instructions (DuPont NEN, MA). Unbound iodine wasseparated by gel filtration and radiolabeled eotaxin was aliquoted andstored at −80° C. until use. The specific activity of the labeledeotaxin was 4.1×10⁴ cpm/pmol.

Ligand Binding Assay

¹²⁵I-labeled human eotaxin was prepared as described above. ¹²⁵I-labeledRANTES, ¹²⁵I-labeled MCP-3, and ¹²⁵I-labeled MIP-α were purchased fromDuPont NEN, MA. Binding of RANTES, MIP-1α and human eotaxin was carriedout in binding buffer consisting of 50 mM HEPES supplemented with 1 mMCaCl₂, 5 mM MgCl₂ and 0.5% BSA. Aliquots of 50 μl (5×10⁵) cells wereadded to Eppendorf tubes, incubated first with unlabeled chemokines,then 0.1 nM ¹²⁵I labeled chemokines as indicated below. The finalreaction volume was 200 μls. Total binding was carried out in theabsence of unlabeled chemokines, and non-specific binding was determinedby incubating cells with radiolabeled chemokine in the presence of 250nM of cold chemokine. At the end of incubation, cells were washed 3times in binding buffer plus 0.5 M NaCl. The cell pellets weretransferred into LP3 tubes and counted in a gamma counter.

The binding of MCP-3 was carried out in Hank's Balanced Salt Solution(HBSS) supplemented with 0.5% BSA and 0.1% sodium azide. After a 30minute incubation at 37° C., the cells were laid onto 800 μl of 20%sucrose and spun at 3000 rpm to separate unbound isotope. The tubes weresnap-frozen on dry-ice/ethanol and the tips of the tubes containing thecell pellets were cut off and counted. All experiments were carried outusing duplicates and repeated at least three times. Scatchard analysiswas performed with Microsoft Excel using a linear curve fit.

Competitive Binding Studies

Human eosinophils were purified as described in Example 4, and thebinding of human eotaxin to eosinophils was investigated. ¹²⁵I-labeledeotaxin was incubated with purified eosinophils in the presence ofincreasing concentrations of ‘cold’ eotaxin, ‘cold’ RANTES, ‘cold’MIP-1α or ‘cold’ MCP-3. FIG. 7 shows that radiolabeled eotaxin was ableto bind to human eosinophils, could be inhibited efficiently by ‘cold’eotaxin, and less efficiently by MCP-3. RANTES and MIP-1α were not ableto compete with eotaxin under the conditions used. Data from competitivebinding by unlabeled eotaxin was used to produce a Scatchard plot (FIG.8), which revealed a single class of high affinity binding sites foreotaxin, a Kd of 4.7 nM, and 2.4×10⁴ binding sites per cell. Theobserved dissociation constant is analogous to other chemokine-receptordissociation constants.

In another experiment, purified human eosinophils were incubated withincreasing concentrations of ‘cold’ RANTES, ‘cold’ eotaxin, ‘cold’ MCP-3or ‘cold’ MIP-1α. 0.1 nM radiolabeled RANTES was added, and binding wascarried out at room temperature for 60 minutes. The results of thisexperiment indicated that eotaxin could completely inhibit ¹²⁵I-RANTESbinding to eosinophils (FIG. 9A).

The competitive binding of MCP-3 and eotaxin was also assessed. Purifiedhuman eosinophils were incubated with increasing concentrations of (a)‘cold’ MCP-3 or ‘cold’ eotaxin, and (b) radiolabeled MCP-3. MCP-3binding to eosinophils was completely blocked by eotaxin with a similaraffinity as MCP-3 (FIG. 9B).

To assess MIP-1α binding, butyric acid differentiated HL-60 cells wereincubated with ‘cold’ MIP-1α, ‘cold’ eotaxin, ‘cold’ RANTES, ‘cold’MCP-3 or ‘cold’ IL-8. 0.1 nM radiolabeled MIP-1α was then added, and thebinding assay was carried out as described above. Total binding wasmeasured in the absence of any competitors. MIP-1α, which hardly boundto eosinophils, showed good binding to HL-60 cells and this binding wasnot significantly affected by up to 1,000 fold excess of eotaxin underthe conditions used (FIG. 10). These data indicate that a MIP-1α/RANTESreceptor (probably CC CKR-1 (Neote et al., Cell, 72: 415-25 (1993)) isexpressed on HL-60 cells, but is not detectably expressed oneosinophils, and that eotaxin binds to a receptor that is distinct fromthis receptor. RANTES and MCP-3 may share the receptor (designated theCKR-3 receptor; see below) with eotaxin but bind with a lower affinity.

Example 7 Eotaxin Binds to and Mediates Chemotaxis Through a Novel CCChemokine Receptor

Two CC chemokine receptors have been described in the literature todate: (1) the MIP-1α/RANTES receptor (Neote, K. et al., Cell, 72: 415-25(1993); Horuk, R. et al., WO 94/11504, published May 26, 1994; Gao,J.-I. et al., J. Exp. Med., 177: 1421-1427 (1993)), and (2) the MCP-1receptor (Charo, I. F. et al., Proc. Natl. Acad. Sci. USA, 91: 2752(1994)). The MIP-1α/RANTES receptor binds RANTES in addition to MIP-1α,and the MCP-1 receptor has been implicated in both MCP-1 and MCP-3binding. In addition, a novel C—C chemokine receptor designated C—Cchemokine receptor 3 (CKR-3; also referred to as EosL2 receptor) hasbeen identified (U.S. Ser. No. 08/375,199, entitled “Novel GProtein-Coupled Receptor Gene and Methods of Use Therefor”, filed Jan.19, 1995, the teachings of which are incorporated herein by reference intheir entirety.) The ability of various chemokine receptors to mediateeotaxin binding and/or a functional effect (chemotaxis) in response toeotaxin was determined.

CKR-3 Gene

Eosinophil isolation and purification was performed as described inExample 4. mRNA for RT-PCR (Reverse transcription-polymerase chainreaction) was extracted directly from purified cells using theMicro-FastTrack™ mRNA isolation kit purchased from Invitrogen. 20-50 ngof mRNA was reverse transcribed using a GeneAmp® RNA PCR kit(Perkin-Elmer) with oligo dT and/or random hexamers as primers in a 20μl final volume as specified by the manufacturer. 2-5 μl of this cDNA(reverse transcribed eosinophil message) was mixed with 200 μM dNTPs and50-100 pmol of degenerate primers in a 50 μl volume.

PCR products were assessed and separated by agarose gel electrophoresis,and appropriately sized fragments were purified and subcloned using thepCR-Script™ SK+ cloning kit (Stratagene). By sequence analysis of PCRfragments, generated from degenerate oligos, a 201 bp partial cDNA clonein pCR-Script was identified. The 201 bp PCR fragment was obtained fromamplification using primer 2a-2 (forward (SEQ ID NO:9); 5′-AC CTG GCCITG GCI GAC CTM CTC TT) and primer 3R (reverse (SEQ ID NO:10); CTG GCRATG GAC CGG TAI CAG GTR CGG-5′). This partial clone, designated Eos L2(also referred to as L2 and EL2), was used for genomic libraryscreening.

A human genomic phage library constructed in the EMBL3 SP6/T7 vector,purchased from CLONTECH Laboratories, Inc. (Palo Alto, Calif.), wasscreened with the 201 bp PCR fragment to obtain a full-length clone. Toprepare the PCR probe, the 201 bp fragment was released from thepCR-Script vector with restriction enzymes EcoRI and Not I. Thisdigestion resulted in a fragment of 240 bp comprised of the 201 bpfragment plus 39 base pairs of polylinker from the vector. The fragmentwas separated from vector by electrophoresis through agarose gel, andpurified by Magic Mini Prep (Promega Corp. Madison, Wis.) as recommendedby the manufacturer. Approximately 200 ng of material was labeled withthe Random Primed DNA Labeling Kit purchased from Boehringer Mannheimfollowing the manufacturer's recommended labeling protocol.

Approximately 25,000 plaque forming units were mixed with 600 μl of anovernight bacterial culture of E. coli strain K802 provided with thelibrary in NZCYM top agarose and plated on 150 mm petri dishescontaining NZCYM agar (NZYCM broth, Agar and Agarose were purchased fromGibco/BRL). After incubation at 37° C. for 7 hours, the plates wereoverlaid with BA-85 nitrocellulose membranes (Schleicher and Schuell,Keene, N.H.) for 5 minutes to allow transfer of phage to membrane. Themembranes were then soaked for 5 minutes in Denaturing Solution (1.5 Msodium chloride, 0.5 N sodium hydroxide) followed by neutralization in1.5 M sodium chloride, 0.5 M Tris, pH 8.0. The filters were allowed toair dry for 15 minutes and then baked for two hours at 80° C. undervacuum. For Southern blots, hybridization was in 6×SSC (1×SSC is 0.15 Msodium chloride, 0.015 M sodium citrate) containing 5×Denhardt'ssolution (1×Denhardt's solution is 0.02% bovine serum albumin, 0.02%ficoll, 0.02% polyvinyl-pyrolidone), 10% w/v dextran sulfate, 2% SDS,and sheared salmon sperm DNA (100 μg/ml) overnight at 65° C. Themembrane was rinsed twice in 2×SSC, 0.5% SDS at 65° C. followed by twowashes (15 min each) in 0.2×SSC, 0.5% SDS at 65° C.

One genomic phage clone, designated Eos L2.8, contained an insert whichcomprises the 1.8 kb Hind III fragment seen on Southern blots (completeinsert size was not determined, but is ˜17 kb). Phage clone Eos L2.8 wasdigested with Hind III restriction enzyme and electrophoresed on anagarose gel. A Hind III fragment of approximately 1.8 kb was cut out,electroeluted from agarose, phenol/chloroform extracted and precipitatedwith ethanol. The 1.8 kb fragment was resuspended in water and ligatedinto the Hind III site of the pBluescript II KS+ vector (Stratagene)followed by transformation into DH5α competent cells purchased fromGibco/BRL.

Both strands of this Hind III fragment were sequenced, and the fragmentwas found to contain the entire amino acid coding region for a humanCKR-3 receptor (Eos L2 receptor). The sequence is presented in FIG.15A-15D (SEQ ID NO:5 and SEQ ID NO:6).

FLAG-Tagged CKR-3 (Eos L2) Receptor Construct

A CKR-3 receptor fusion protein was constructed as follows:

1. A FLAG-PAF receptor construct in pCDM8 (constructed as reported in D.Kunz, N. P. Gerard, and C. Gerard (1992), J. Biol. Chem. 267: 9101-9106)was double digested with Hind III and EcoRI to release a fragmentcontaining nucleotides which encode the FLAG peptide. The nucleotidesequence is AAGCTTCCA GCA GCC ATG GAC TAC AAG GAC GAC GAT GAC AAA GAATTC(SEQ ID NO:11). The amino acid sequence is MDYKDDDDKEF (SEQ ID NO:12).The Hind III/EcoRI fragment containing the FLAG nucleotides wassubcloned into the Hind III/EcoRI sites of the pcDNA3 vector(Invitrogen, San Diego, Calif.) giving rise to pcDNA3/FLAG.

2. The pBluescript II KS+ vector containing the 1.8 kb CKR-3 Hind IIIfragment was digested with BamHI and Xho I to release a 1.261 kbfragment. This BamHI-XhoI fragment contains nucleotides encoding CKR-3amino acids 91 through the stop codon plus the same 3′ untranslatedregion and 21 bp of pBluescript II KS+ vector.

3. Two PCR primers were generated to amplify the 5′ end of the CKR-3gene, but removing the first Met and engineering in an EcoRI site whichwill be compatible with the EcoRI site described above in step 1. The 5′primer (SEQ ID NO:13) was:

     EcoRI 5′-TTAA GAATTC ACA ACC TCA CTA GAT ACThis primer contains an EcoRI site and the first 17 nucleotides of theCKR-3 gene except for the Met codon.

The 3′ primer (SEQ ID NO:14) was:

     BamHI 5′-CATAGT GGATCC AGAATGThis primer primes in the CKR-3 gene just 3′ to the BamHI site.Amplification with these two primers using the pBluescript II KS+ vectorcontaining the 1.8 kb CKR-3 fragment as template will amplify a 280 bpfragment containing the 5′ end of the CKR-3 gene which can be digestedwith EcoRI and BamHI to give a fragment for ligation as described below.

Conditions for amplification were: 100 ng of pBluescript II KS+containing the 1.8 kb CKR-3 fragment was combined with 200 μM dNTPs and50 pmol of primers in a 50 μl reaction volume. The final magnesiumconcentration was 2.5 μM and the pH was 8.0. The fragment was amplifiedwith 25 cycles of 94° C., 30 sec; 55° C., 30 sec; 72° C., 30 sec. Theamplified product was separated on agarose gel and purified byelectroelution as described above. The fragment was digested with EcoRIand BamHI purified again on agarose gel.

4. For construction of the Flag-tagged CKR-3 gene, the pcDNA3 vectorcontaining the FLAG fragment (described in step 1) was digested withEcoRI and Xho I. The vector fragment (an EcoRI-XhoI fragment comprisingthe FLAG coding sequence) was separated from the polylinker fragment byelectrophoresis, and the vector fragment was purified as described forother electroeluted fragments. The vector fragment was combined with theEcoRI-BamHI fragment generated by PCR in step three. These two fragmentswere combined with the 1.261 kb BamHI-XhoI fragment from step two. Allthree fragments were triple ligated together to yield the FLAG-taggedCKR-3 receptor in pcDNA3. Ligated DNA was transformed into DH5α.

L1-2 Transfectants

The mouse L1-2 cell line is derived from a pre-B lymphoma, and wasobtained from Dr. Eugene Butcher (Stanford University, Stanford,Calif.). L1-2 transfectants expressing IL-8 A receptor (a C—X—Cchemokine receptor), IL-8 B receptor (a C—X—C chemokine receptor), orthe MIP-1α/RANTES receptor (also referred to as C—C chemokinereceptor 1) were obtained from Dr. Eugene Butcher (Murphy P. M. and H.L. Tiffany, Science, 253: 1280-1283 (1991); Murphy et al., WO 93/06299;Holmes, W. E. et al., Science, 253: 1278-1280 (1991); Neote, K. et al.,Cell, 72: 415-425 (1993); Horuk, R. et al., WO 94/11504, published May26, 1994; Gao, J.-I. et al., J. Exp. Med., 177: 1421-1427 (1993)).

L1-2 cells were also transfected with a linearized clone encoding C—Cchemokine receptor 3 (CKR-3)), or a clone encoding MCP-1 receptor type B(Charo, I. F. et al., Proc. Natl. Acad. Sci. USA, 91: 2752 (1994)). Thereceptors encoded by the latter clones are tagged with a FLAG epitope atthe N-terminus which is encoded by the pcDNA expression vector(Invitrogen, San Diego, Calif.).

The transfection conditions were as follows: 25 million L1-2 cells in1.0 ml of transfection buffer (Hank's Balanced Salts Solution plus 20 mMHepes, pH 7.05, 137 mM NaCl, 5 mM KCl, 0.7 mM Na₂HPO₄, and 6 mMdextrose) were incubated for 10 minutes at room temperature with 20 μgof linearized DNA. The cell/DNA mixture was transferred to anelectroporation cuvette (available from BioRad, Richmond, Calif.) andsubjected to electroporation using a BioRad electroporator set to 250volts, 960 μF. The electroporated cells were allowed to stand at roomtemperature for 10 minutes followed by transfer to 10 mls of media. Thecells were incubated for 48 hrs followed by the addition of mediabringing the volume to 50 mls. 0.8 mg/ml of Geneticin (Gibco/BRL) wasadded to the cells which were then plated over five 96-well microtiterplates. After about 2 weeks under selection, the wells were screenedindividually by immunofluorescence and flow cytometry using an antibodyreactive with the FLAG epitope (M1 monoclonal antibody; Kodak). Stabletransfectants expressing receptor on the surface were screened foreotaxin binding and chemotactic activity in vitro.

CKR-3-Transfected Cells Bind to Human Eotaxin

Binding buffer consisted of 50 mM HEPES supplemented with 1 mM CaCl₂, 5mM MgCl₂ and 0.5% BSA. ¹²⁵I-labeled eotaxin (10 nM) was incubated with5×10⁵ CKR-3-transfected cells or with untransfected L1-2 cells in 200 μlof binding buffer, and binding was carried out at room temperature for60 minutes. Binding was determined in the presence of 125 nM unlabeledeotaxin or in the absence of competitor. FIG. 11 shows that significantbinding of eotaxin was achieved under these conditions, under whicheosinophils also efficiently bind eotaxin. Binding to CKR-3transfectants was specific, since it could be inhibited by unlabeledeotaxin and untransfected L1-2 cells failed to bind.

Protocol for Transfectant Chemotaxis

For assessing chemotaxis of transfectants, the transendothelial assaydescribed in Example 4 was modified as follows. 600 μl of assay media(50% RPMI1640, 50% M199, 0.5% endotoxin free BSA) containing thechemokine to be tested was added to the bottom chamber of the assayplate (Collaborative Biomedical, Cat. No. 40575). 10⁶ L1-2 transfectantsor L1-2 wild type cells were added to the upper chamber in a 100 μlvolume. The cells were incubated for 4 hr-overnight at 37° C. The upperchamber was removed and cells which migrated through the membrane insertof the upper chamber were counted.

Chemotaxis of a Pre-B Lymphoma Line Transfectants Expressing ChemokineReceptors

Untransfected L1-2 cells do not respond to any human chemokines,including IL-8, MCP-1, RANTES, MIP-1α and eotaxin. However, whentransfected with DNA encoding the IL-8RA, IL-8RB, MIP-1α/RANTES, orMCP-1 receptor, L1-2 cells were able to chemotax in response to specificligands (FIGS. 12A-12D). FIG. 12C shows that L1-2 cell transfectantsexpressing the human MIP1-α/RANTES receptor chemotaxed strongly toMIP-1α, and weakly to MCP-3. In contrast, these cells were notresponsive to human eotaxin over a wide dose range (1 ng/ml to 1000ng/ml) (FIG. 12C illustrates the effect of 100 ng eotaxin). Likewise,L1-2 cells transfected with DNA encoding the human MCP-1 receptor (Btype) chemotaxed strongly in response to MCP-1 and weakly in response toMCP-3, but not other ligands including eotaxin. These studies indicatedthat these receptors are not functioning in eotaxin chemotaxis, or atleast are unable to when introduced by transfection into L1-2 cellsunder the conditions used here. The presence of these receptors inmonocytes and activated T cells, which are unresponsive to eotaxin,further indicates that eotaxin does not bind to or function througheither of these receptors.

FIG. 12E shows the response of L1-2 cells transfected with a C—C CKR-3clone encoding a novel C—C chemokine receptor identified from humaneosinophils (U.S. Ser. No. 08/375,199, filed Jan. 19, 1995). These cellschemotaxed strongly in response to eotaxin, and less so in response toRANTES. In contrast, L1-2 transfectants expressing CKR-3 did not respondto the other chemokines tested under the conditions of the assay. Theseresults indicate that eotaxin is a principal ligand for the CKR-3receptor. Furthermore, these results support the conclusion that C—CCKR-3 and human eotaxin are an important receptor-ligand pair foreosinophil chemotaxis.

A monoclonal antibody (LS26-5H12) reactive with CKR-3 was used in FACSanalysis of human eosinophils, peripheral blood lymphocytes, monocytes,neutrophils, and activated T cells (Example 4). Cells were stained withmonoclonal antibody LS26-5H12, followed by FITC-anti-mouse Ig (JacksonImmunoResearch Laboratories, Inc.). Fc receptor binding was controlledfor by using an excess of normal human serum.

All eosinophils were stained with anti-CKR-3 antibody LS26-5H12 (notshown). Monocytes were weakly positive for immunofluorescence. A smallproportion of lymphocytes were positive for staining, and substantiallyall of the activated T cells were weakly stained with the antibodyLS26-5H12, indicating that T cells express receptor which is upregulatedupon T cell activation. Neutrophils were not significantly stained byLS26-5H12 antibody under the conditions of the assay.

As indicated above, on eosinophils there is a single class of bindingsites for eotaxin, with a Kd of 4.7 nM, and 2.4×10⁴ binding sites percell. The competition studies described herein indicate that eotaxinbinds to a receptor which is distinct from the MIP-1α/RANTES receptordescribed by Neote et al. (Cell, 72: 415-25 (1993)). As indicated bystudies with transfectants expressing CKR-3 protein, CKR-3 can mediateeotaxin binding and chemotaxis in response to eotaxin. In addition,antibody LS26-5H12 detects CKR-3 on eosinophils. Taken together, thedata support the conclusion that CKR-3 on eosinophils accounts for some,if not all, of the eotaxin binding and responsiveness of eosinophils.

Example 8 Monoclonal Antibodies (MAbs) Reactive with Human Eotaxin

MAbs reactive with human eotaxin were generated by immunizing mice witha synthetic polypeptide corresponding to the 74 amino acids of predictedmature eotaxin (amino acids 24-97). Female Balb/C mice were immunizedwith 50 μg of the polypeptide in PBS 3 times at 2 week intervals. Micewere injected intra-peritoneally with the polypeptide, using Freund'scomplete (first injection) and incomplete adjuvant (second injection).The final immunization was injected intravenously without adjuvant.

One successful fusion was performed which generated over 5,000hybridomas. Four days after the final injection, the spleen was removedand a single cell suspension prepared in serum free DMEM media. Thesecells were fused with the hybridoma fusion partner SP2/0, according toGalfre, G. et al. (Galfre, G. et al., Nature, 266: 550-552 (1977)). 20ml of spleen cells and 20 ml of SP2/0 were combined, spun at 800 g for 5min and the media removed. A solution of 50% Polyethylene glycol 1500(Boehringer Mannheim, Indianapolis, Ind.) prewarmed to 37° C. was addedto the cell pellet over 2 min, followed by 10 ml of DMEM media over 3min. The cell suspension was spun at 400 g for 3 min and the supernatantremoved. The pellet was resuspended gently in DMEM media containing 20%fetal calf serum, 2 mM L-glutamine, 100 units/ml penicillin, 100 μg/mlstreptomycin sulfate, and HAT selection media (Boehringer Mannheim,Indianapolis, Ind.). Cells were plated into 96 well flat bottommicrotiter plates at 200 μl/well.

Ten days later, supernatants from the wells were screened for reactivityagainst the human eotaxin polypeptide using an enzyme-labeled anti-mouseantibody (Horseradish peroxidase-labeled anti-mouse IgG) (Jackson) in anELISA assay (Current Protocols in Immunology, 1992, Coligan, J. E., A.M. Kruisbeek, D. H. Margulies, E. M. Shevach, and W. Strober, Editors,(John Wiley and Sons, New York, N.Y.), Unit 2.1.3). Approximately 50mAbs were selected that showed strong reactivity against the syntheticpolypeptide. Hybridomas of interest were subcloned using limitingdilution.

Western Blot Analysis Using Anti-Eotaxin Monoclonal Antibody 6H9

The specificity of mAb 6H9 for human Eotaxin was confirmed by Westernblot analysis. 2 μg each of various chemokines (MCP-1, MCP-2, MCP-3,RANTES, Eotaxin, MIP-1α, or MIP-1β) were mixed with non-reducing samplebuffer, boiled, and applied to individual lanes of an SDS-polyacrylamidegel. Gels were run using a Biorad Mini-Protean II cell, and transfer ofproteins to nitrocellulose was performed for 1 hr using 100V. SDS-PAGEand Western blotting were performed as described in Current Protocols inImmunology, Unit 8, Coligan et al., Eds., (John Wiley & Sons, New York,N.Y.), 1992, except that pre-poured 10-20% polyacrylamide gradient gelswere used (BioRad, Hercules, Calif.). The nitrocellulose membranes wereincubated with monoclonal antibody 6H9 as primary antibody for 1 hr,washed, and reacted with goat anti-mouse Ig conjugated with horseradishperoxidase (Jackson Labs), as described in Current Protocols inImmunology, 1992, Coligan, J. E., A. M. Kruisbeek, D. H. Margulies, E.M. Shevach, and W. Strober, Editors, (John Wiley and Sons, New York,N.Y.), Unit 8.10.7. Reactive bands were visualized usingdiaminobenzidene as the chromagen.

Monoclonal antibody 6H9 reacted with a band of approximately 6 kDapresent in the lane containing synthetic eotaxin (predicted matureprotein consisting of amino acids 24-97), but was not reactive with anyof the other chemokines tested, including MCP-1, MCP-2, MCP-3, RANTES,MIP-1α, and MIP-1β.

Anti-Eotaxin Monoclonal Antibodies Inhibit Eotaxin Binding toEosinophils Antibody-Mediated Inhibition of Eotaxin Binding

Eighteen monoclonal antibodies selected by ELISA were tested for theirability to block eotaxin binding to its receptor on eosinophils. Bindingbuffer consisted of 50 mM HEPES, 1 mM CaCl₂, 5 mM MgCl₂ and 0.5% BSA. 50μL of tissue culture supernatant from eighteen different anti-eotaxinhybridomas were each incubated with 5 μl (10 nM) ¹²⁵I-labeled eotaxin(prepared as described in Example 6) at room temperature for 10 minutes.50 μl (5×10⁵ cells) of purified human eosinophils (see Example 4) werethen added, final volume was adjusted to 200 μl with binding buffer, andbinding was carried out at room temperature for 60 minutes. As negativecontrols, 50 μl of culture medium (no antibody) or an anti-IL-8 receptorB antibody were added in lieu of anti-eotaxin antibody. At the end ofincubation, cells were washed 3 times in binding buffer plus 0.5 M NaCl.The cell pellets were transferred into LP3 tubes and counted in a gammacounter.

Of eighteen anti-eotaxin monoclonal antibodies tested, five showedsignificant inhibition of ligand binding (FIGS. 13A-13B; 3C7, 4A3, 9H3,10H2, and 8A4-1).

Example 9 Upregulation of Eotaxin Expression at a Site of EosinophilInvolvement

Immunohistochemical analysis for human eotaxin protein was performed onformalin-fixed, paraffin-embedded samples of human nasal polyps andadjacent uninvolved nasal mucosa using techniques previously described(Ringler, D. J. et al., Lab. Invest., 56: 313 (1987); Ringler, D. J. etal, Clin. Immunol. Immunopathol., 49: 349 (1988); and Ringler, D. J. etal., Am. J. Pathol., 126: 199 (1987)). Tissue was obtained from a human(believed to be an allergic rhinitis patient). Briefly, deparaffinizedsections were post-fixed in 100% methanol for 5 minutes at 4° C.,followed by blocking with PBS/10% goat serum for 30 minutes at roomtemperature. Anti-human eotaxin monoclonal antibody 6H9 (Example 8) orirrelevant mAb was then used as neat tissue culture supernatant,followed by biotinylated goat anti-mouse IgG (Vector Laboratories,Burlingame, Calif.), and subsequently by avidin-peroxidase complexes(Vector Laboratories, Burlingame, Calif.). Diaminobenzidine (DAB) wasused as the chromagen.

There was a direct correlation between eosinophil infiltration withinthe mucosa and submucosa of the polyp and eotaxin expression to residentcells and leukocytes. Specifically, in areas of eosinophil localization,there was an increase in the number of anti-eotaxin immunoreactivemacrophages, mast cells, epithelial cells, and eosinophils, and whencompared to uninvolved nasal mucosa, a concomitant increase in stainingintensity. These results were confirmed using anti-eotaxin monoclonalantibodies designated 6D6, 5H2, 5E9 and 1H12 (Example 8).

The colocalization of elevated levels of eotaxin and eosinophils ininflamed tissue, as assessed immunohistologically with anti-eotaxinmonoclonal antibodies supports the in vivo significance of eotaxin tothe process of inflammation.

Example 10 Protocol for Eosinophil Recruitment to Skin

A male adult rhesus monkey was injected intradermally at 9 sites on theback with 0.1 ml of the following:

-   -   10, 100 or 1000 pmol of eotaxin in buffer    -   10, 100 or 1000 pmol of RANTES in buffer    -   10, 100 or 1000 pmol of bovine serum albumin (BSA) in buffer

Buffer was Dulbecco's Phosphate buffered saline. Full-thickness skinbiopsies (6 mm) were taken from these sites at 4 hours post-injection.These tissues were fixed in formalin, embedded in paraffin and sectionedfor histological analysis by staining with hematoxylin and eosin.

Quantitative, computer-assisted, morphometric analysis of skin sectionswas performed using a Leica Quantimet 500 Image Analyzer. The relativedensity (number cells/area²) of eosinophils was enumerated on at least 5random fields/sections just adjacent to the post-capillary venules ofthe superficial vascular plexus. Cells were selected based on the colorwavelength generated from eosin-stained cytoplasmic granules ofeosinophils, and color selection criteria were identical on all sectionsanalyzed. The number of eosinophils/area^(2 (mm)) of dermis wascalculated as the mean±1 SEM and graphically depicted (FIG. 14).

Results

The results showed no recruitment of eosinophils with BSA at the 10 or100 pmol doses, and only a rare isolated eosinophil at 1000 pmol. Thegreatest eosinophil recruitment was observed at the injection site for1000 pmol of human eotaxin, which was characterized histologically byfoci consisting of 5-10 eosinophils adjacent to the postcapillaryvenules of the superficial vascular plexus in the dermis, as well asclusters of eosinophils scattered throughout the dermal collagenbundles. RANTES elicited a substantially (approximately 10-fold) lowerresponse at 100 pmol, with insignificant recruitment at the 10 pmol dose(FIG. 14).

EQUIVALENTS

Those skilled in the art will be able to recognize, or be able toascertain, using no more than routine experimentation, many equivalentsto the specific embodiments of the invention described herein. Suchequivalents are intended to be encompassed by the following claims.

1. An isolated nucleic acid which encodes a human eotaxin or afunctional portion thereof.
 2. The isolated nucleic acid of claim 1,wherein the isolated nucleic acid is recombinant.
 3. The isolatednucleic acid of claim 1, wherein said nucleic acid encodes a polypeptidehaving the amino acid sequence set forth in FIG. 2 or a functionalportion thereof.
 4. The isolated nucleic acid of claim 3, which is arecombinant nucleic acid.
 5. The isolated nucleic acid of claim 3,wherein said nucleic acid is essentially pure.
 6. The isolated nucleicacid of claim 3, said nucleic acid having a nucleotide sequence selectedfrom the group consisting of the nucleotide sequence of FIG. 1, thenucleotide sequence of FIG. 2, a nucleotide sequence which hybridizesthereto.
 7. The nucleic acid of claim 6, wherein the polypeptide is aneosinophil chemoattractant.
 8. A recombinant construct comprising anucleic acid of claim
 1. 9. The recombinant construct of claim 8,wherein the recombinant nucleic acid is operably linked to an expressioncontrol sequence.
 10. The recombinant construct of claim 9 comprising anucleic acid, wherein said nucleic acid encodes a polypeptide having theamino acid sequence set forth in FIG. 2 or a functional portion thereof.11. The recombinant construct of claim 9, wherein the nucleic acid isoperably linked to an expression control sequence. 12-15. (canceled) 16.A host cell containing an isolated, recombinant nucleic acid of claim 2.17. The host cell of claim 16, wherein the nucleic acid is operablylinked to an expression control sequence, whereby the encoded protein orfunctional portion thereof is expressed when the host cell is maintainedunder conditions suitable for expression.
 18. The host cell of claim 17,wherein the expressed protein is an eosinophil chemoattractant.
 19. Afusion protein comprising a human eotaxin polypeptide or a portionthereof having at least one function or an immunological propertycharacteristic of a human eotaxin. 20-21. (canceled)
 22. A nucleic acidconstruct comprising a nucleic acid containing a coding sequence whichencodes a fusion protein comprising of claim 19, wherein the codingsequence is operably linked to an expression control sequence. 23-24.(canceled)
 25. A method for producing a human eotaxin or functionalportion thereof comprising maintaining a host cell containing arecombinant nucleic acid encoding a human eotaxin polypeptide orfunctional portion thereof under conditions suitable for expression ofthe nucleic acid, whereby the encoded protein is expressed and a humaneotaxin polypeptide is produced.
 26. The method of claim 25 furthercomprising the step of isolating the human eotaxin polypeptide. 27-28.(canceled)
 29. A method of diagnosis of an eotaxin associated humandisease or condition comprising: a) contacting a sample from a humanwith an antibody which binds an isolated human eotaxin under conditionssuitable for specific binding of said antibody to human eotaxin; and (b)detecting antibody-eotaxin complexes.
 30. A method of modulating atleast one function of human eotaxin, comprising the step of contactingsaid human eotaxin with an inhibitor or promoter of at least onefunction of human eotaxin.
 31. A method of treating an inflammatorydisease or condition, comprising administering to a human atherapeutically effective amount of an inhibitor of a human eotaxinpolypeptide, whereby inflammation is reduced. 32-37. (canceled)
 38. Amethod for inhibiting tumor growth or inducing tumor regression in apatient in need thereof comprising administering to the patient ananti-tumor amount of a human eotaxin, a functional portion or variantthereof. 39-41. (canceled)